Great Neck South Physics Lab Manual

Transcription

Great Neck South
Physics Lab Manual
1-
Scale Drawing, Angle Measure, Smart Labs
02-19
40 min
2-
Measurements Lab
20-31
80 min
3-
Vector Altitude Lab
32-33
40 min
4-
Forces as Vectors
34-35
5-
Using A Spark Timer
36-45
40 min
6-
Acceleration with Car and Spark Timer
46-55
80 min
7-
Free Fall
56-61
40 min
8-
Projectile - Spudzooka
62-65
80 min
9-
Linear Equilibrium II
66-67
10 -
Newton's Law
68-73
40 min
11 -
Friction
74-83
80 min
12 -
Centripetal Force
84-89
80 min
13 -
Measuring Power
90-95
40 min
14 -
Springs - Hooke's Law and Potential Energy
96-101
80 min
15 -
Static Electricity Lab
102-105
80 min
16 -
Resistance of a Wire and Ohms Law
106-115
80 min
17 -
Introduction to Electronic Components
116-125
80 min
18 -
Series Circuits
126-133
80 min
19 -
Parallel Circuits
134-141
80 min
20 -
Magnetic Field Mapping
142-143
80 min
21 -
Strength of a Magnetic Field
144-149
80 min
22 -
Pendulum Lab
150-155
80 min
23 -
Waves Pulses on a Coil Spring
156-159
24 -
Speed of Sound
160-161
40 min
25 -
Refraction with Laser
162-167
80 min
APPENDIX
A1 -
Work Relationships in the Inclined Plane
A01-A04
A2 -
Simple Harmonic Motion with a Spring
A05-A06
A3 -
Waves on a Coil Spring
A07-A10
A4 -
Reflection From Plane Surfaces
A11-A12
A5 -
Refraction II
A13-A14
A6 -
Diffraction of Light
A15-A16
A7 -
Interference of Waves
A17-A18
1
Intro LAB 1
Scale Drawings,
Angle Measure and
Interpretation of
Lab Data
Name: ______________________________________________________________________
2
1. Angle Measure – Using Protractors
A protractor is the device that we usually use to measure
angles.
Use of a protractor is rather simple. Be precise when using a protractor, make sure the base of the protractor
lines up correctly with the line you are measuring the angle from and be sure the point where the lines intersect is
directly in the center point of the protractor.
Often you have to extend the lines that make the angle you are measuring so that they will fall on the
scale and you can accurately read where they line up.
Using a protractor is best learned by viewing examples. Let’s look at a few examples.
You want to measure the angle in the bottom left corner of this triangle. Place the protractor as shown below. Be
sure that the point on the left corner of the triangle is in the center of the protractor and the bottom line of the
triangle is exactly lined up on the 0 degree part of the protractor
Angle we are measuring
Zero degree mark
Now all we do is look at the scale on the protractor to see where the line hits it. Note there are two scales on the
protractor along the arc (one on the top and one underneath it). Looking at our scale, we see the angle is either
62° or 122°. Looking at the triangle we know the angle is less than 90 so we choose the 62° measure.
Another protractor example.
3
You are measuring the angle
between the two sides that
intersect at the top
You look to see where the line
intersects the scale.
This line is
on the 0
degree mark
Again you know the angle must be
less than 90 degress.
So you choose the 66 degree
measure.
66 degrees away
from the 0 degree
line
Sometimes you have to be creative to measure the angles of real life things because they can be a little awkward.
One trick you might try is to use a string in various ways so you can extend the side of something and get a
decent angle measure. You could also try to trace a portion of something on paper, or fold the paper to imitate
the angle that you want to measure.
4
2. Scale Drawings
What is a "Scale" Drawing?
A scale drawing is a miniature version of a real life thing that is drawn to proportion so that if you took the drawing
and enlarged it to be the actual size, it would exactly resemble the real life object. When making a scale drawing
be sure to use a ruler and a protractor. Measure the lines you are going to draw, make them straight and
measure angles properly with a protractor if needed.
Making your own Scale Drawing
The distance from NY to CA is approximately 3000 miles. If you wanted to make a scale drawing of the road on
your paper, you can't make a line that is 3000 miles long. You have to establish a scale.
When making a scale drawing, ALWAYS USE THE CENTIMETERS PART OF YOUR RULER (cm). Each
centimeter is broken into 10 equal divisions and is easier to use.
The first part of making a scale drawing is choosing a scale. You should choose your scale so that your drawing
is not too small and not too large. It takes some practice and experience to choose a scale but a little trial and
error will give you an adequate drawing. You can often look at the largest dimension you need to draw to
determine what scale you should use.
In the example above with the road from NY to CA, a scale of 1 cm = 500 mi would be appropriate. With this
scale, your road would be 6 cm long.
Your scale will always be of the form
X units of the real life dimension
[ 1 cm = X ] which states that every 1 cm you draw on paper represents
5
A SCALE DRAWING EXAMPLE
You want to draw a side view of a house on a piece of paper to scale. You measure the house and find out that it
is 45 feet long and 21 feet high.
We have to draw two lines to make the rectangle, which will be the house. I will chose a scale of [1 cm = 5 ft ]
The scale factor we just found is actually like a new conversion factor. It is telling us that (1 cm = 5 ft)
(its sort of like the conversion factors we used before such as (1 ft = 12 in), except this one is special only for this
example). We can use it the same way we used our other conversion factors in order to determine how long we
should actually draw each line on the paper.
We have to draw two lines, one that will represent the length of 45 ft and the other for the height of 21 ft. Lets
determine how long we should draw them on the page.
Length (45 ft)
Height (15 ft)
What we did here was use our scale factor (1 cm / 5 ft) to convert our real life
house measurements to values we could draw on paper. The first conversion
showed us that in order to make a line that would represent 45 ft .. we would
have to draw it 9 cm long. This makes sense, think about it: if every 1 cm we
draw represents 5 ft in real life .. then a 9 cm line ( 9x5 = 45 ) would be like a
45 ft line in real life, it works out.
⎛ 1 cm ⎞ = 4.2 cm
21 ft ⎜
⎟
⎝ 5 ft ⎠
Now that we have the paper dimensions, all we have to do is use a ruler to
⎛ 1 cm ⎞ = 9 cm
45 ft ⎜
⎟
⎝ 5 ft ⎠
So we need to draw the length of the house 9 cm long and the height of the house 4.2 cm high. Be sure to note
your scale on your drawing.
The House That Love Built
I start Fires !!
Scale
[ 1cm = 5 ft ]
(If you use a ruler and measure the house, you will see that it is drawn to scale, the man is sort of big though)
6
3.) Introduction to Smart Labs
Science labs are based on real life data. The results and calculations made with lab data should make sense.
Labs are usually based on real life principles that work and when doing a lab write-up you should use your head
and make sure your data is good and what you are doing makes sense.
Rule #1 - Have an idea of what you are doing. If you are warming an object up, and you are taking temperature
readings that are decreasing, then chances are something is wrong. If you are taking time readings and find that
it takes 30 seconds for something to fall off the desk, something is wrong. If repeating the same task over and
over and 1 of the results is very different from the rest, something is most likely wrong with that result. Keep
these things in mind, and ask your teacher if you notice one of these abnormalities … as the year goes on, you
will be able to handle these problems yourself.
Samples
The following data was recorded in an experiment to find the velocity of a car. We observed visually in the
experiment that the car was constantly speeding up. See if you can find any errors that might exist in our
recorded data. Then read below to see what the errors actually are.
Distance of Car
5m
15 m
20 m
25 m
Time trial #1
0.25 sec
0.40 sec
0.50 sec
0.58 sec
Time trial #2
0.027 sec
0.43 sec
0.51 sec
0.60 sec
Time trial #3
0.22 sec
0.42 sec
0.89 sec
0.57 sec
Average Time
0.16 sec
1.25 sec
1.5 sec
0.59 sec
Speed (m/s)
31.25
12.00
13.33
423.7 m/s
Problems with this data
First of all we should notice the speed. In the experiment we noticed the car was speeding up, but this data
shows the car doing weird things, getting slower and such .. it doesn’t make sense. Maybe something is wrong
with our calculations, or maybe something is wrong with the data.
First row - notice time trial #2 compared to the others … it is much to small, it was most likely an error and should
be thrown out or redone if caught while doing the experiment.
Second row - the speed goes down so that doesn’t make sense - maybe our math is wrong. Look at the average
time. If we know something about averages we know this cant be correct and is a math error. If we look at the
data we see that the times don’t change very much at one given distance ... therefore, the average should be
close to any of the time values in that row. The three times 0.40, 0.43 and 0.42 are so close to each other that
the average would be close to them as well. We therefore know that the average time of 1.25 seconds is a
mistake. The person forgot to divide by three when they did the average formula.
Third row - well the speed has increased a little from last time, which is ok, but its still less than the original (there
was a mistake with the original speed to begin with so that might be the problem, but lets check it out anyway).
Look at the times in row three ... 0.50, 0.51, 0.89 ... the last time seems very different from the first two and is
probably an error. It should be thrown out for the analysis or redone if caught before the lab was over
Last row - the speed calculated in the last row seems high, that car would be moving at about 900 miles per hour.
Rule #2 - Data is not perfect, allow some discrepancy to what you think should occur, but be aware when there is
a large amount of error, something might be wrong.
Rule #3 - When comparing multiple values, if you notice that most of your values generally increase, then that is
probably a trend. If the values are more or less the same but go up and down a little bit each time, then chances
are those values should all be the same but experimental error makes them all a little different
7
4.) Working with Graphs
Physics Labs also incorporate the use of graphs to interpret and display data. There are a number of important
facts to know when making graphs.
1.) Your graph should always be labeled with a title, axis labels, and units on the axis labels.
Distance vs Tim e
35
30
Distance (m)
25
20
15
10
5
0
0
1
2
3
4
5
6
Tim e (sec)
2.) Your graph should always have a best fit line drawn on it. (The graph shown above would loose points for
lack of a best fit line). To determine the best type of fit, simply look at your data points to see how the trend is.
In the above graph, we can see that it is clearly indicating a curve. Other data sets will indicate straight line best
fits. Never simply connect all data points.
Distance vs Tim e
35
y = e0.6931x
30
Distance (m)
25
20
15
10
5
0
0
1
2
3
4
5
6
Tim e (sec)
3.) If using Microsoft excel to make graphs, the only type of graph you should ever make is XY scatter, and you
use the one that makes points only. Then, after the graph is made, you right click one of the data points and
choose add trendline. Try out the difference trendlines to see which one fits best.
8
4.) Which values to place on the x and y axis is usually determined for you in a Physics lab and should not be
done simply by your choice. This is a very important point to remember: Graph types are always stated in
the form Y vs. X, and the Y axis value is always listed first with x axis value following it. For example,
Distance vs. Time, means Distance is the y axis value and time is the x axis values. A graph of Density vs. Mass
would indicate Density is on the y axis. In the rare case that you have to choose x and y axis values, the
independent variable goes on the x axis. This means that the variable that is unaffected by the other quantity is
the one that you put on the x axis.
5.) Lab data is not perfect. Most of the time, your graphs will not form perfect curves or perfect lines, that is the
reason for the trendline … it draws a best fit of the data. Occasionally, an error on your part will result in a data
point that skews the graph and changes the trendline. You should be able to notice this error and in this case
you should eliminate the bad data point.
Example.
Distance vs Tim e
25
Distance (m)
20
15
10
5
0
0
1
2
3
4
5
6
Tim e (sec)
Clearly this data is indicating and upwards sloping trend, and the trendline does show that, however, it is being
skewed by the data point at 3 seconds which is clearly a mistake. The point should be removed and you should
note that you did that. The corrected graph is shown below.
Distance vs Tim e
14
12
Distance (m)
10
8
6
4
2
0
0
1
2
3
4
5
6
Tim e (sec)
9
Intro Lab
Name: __________________
When turning in the lab, only turn in from this page forward.
The prior pages are for your reference only
1.) Find any errors or discrepancies in the data shown below. Write what these errors are on
the bottom of the page. Be sure to:
- Refer to the row with the error and state the error
- Then state what to do about it.
An experiment is being conducted in three identical jars full of water. They have three candles held underneath
them to heat the water. The temperature is recorded every minute.
ROW #
Time
Jar 1
Temperature
Jar 2
Temperature
Jar 3
Temperature
Average
temperature
1
1 min
10.06 °C
10.13 °C
10.00 °C
14.56 °C
2
2 min
13.71 °C
13.70 °C
13.71 °C
13.71 °C
3
3 min
20.25 °C
20.50 °C
20.55 °C
20.43 °C
4
4 min
16.20 °C
16.05 °C
16.15 °C
16.13 °C
5
5 min
24.40 °C
24.35 °C
24.42 °C
24.39 °C
6
6 min
28.00 °C
27.98 °C
24.89 °C
26.96 °C
7
7 min
46.60 °C
46.35 °C
46.50 °C
46.48 °C
There are not necessarily errors in every row, but there are 4 total errors in the data. (if there is a single error that
in turn causes other errors, that should be considered only one error total)
Only 1 error is a calculation error.
Other errors are based on the experiment as a whole and what you would expect the results to look like as it
progressed. (read the description of what is actually being done here)
10
2.) The following data is from an experiment measuring pressure in Pascals and volume in cubic meters
Volume (m3)
1
2.5
4
5.75
8
Pressure (Pa)
100
40
25
17.4
12.5
(a) Based on your knowledge from chemistry and gas laws, predict what the shape of the graph Pressure vs.
Volume should look like and draw it below. Be sure to label each axis with units.
(b) Using the real lab data, create a graph of Pressure vs. Volume by hand. Again label everything. Put a best fit
line or curve on the graph.
(c) Your predicted graph and your actual graph might look very different from each other. This relationship is an
inverse relationship. The actual graph you made should be a curve and is the correct look of an inverse graph.
Some students believe an inverse looks like a straight line sloping downward; this is incorrect and will never occur
in a physics lab or test. It is very important to note that inverse graphs are always like the graph you plotted in
the grid.
11
3.) The following data is from an experiment measuring Force in newtons and mass in kilograms.
Mass (kg)
1
2
3
4
5
6
Force (N)
10
23
29
43
50
95
Create a graph of Force vs. Mass by hand and draw a best fit line. Be sure to state any corrections you
need to make for lab data errors, and make those corrections.
4.) Using Microsoft excel, recreate the graphs that you made in steps 2 and 3 and
attach them to the back of this lab report. Your lab should have both the hand
plotted graphs draw on these last two pages as well as the computer generated graphs.
Directions for excel are on the pages that follow.
12
MAKING A GRAPH USING MICROSOFT EXCEL
The only type of graph you should ever use is the XY SCATTER TYPE. (XY scatter has options to make line
graphs or data point graphs)
DO NOT EVER USE THE GENERIC “LINE” GRAPH TYPE .
The first step in making a graph is to create a small table with the values you want to graph. The values you want
to be on the x axis must always come first in the table, and the y axis values come next to them. Refer to sample
table below. Note that the formal statement of this graph would be SPEED vs. TIME since when we state graph
types we always list Y vs. X, however in the chart we need to write the x values first.
Time ( x values)
Speed ( Y values)
1
5
2
10
3
15
DO NOT PUT UNITS ON THE NUMBERS WHEN
GRAPHING THEM
To make your graph, first use the mouse to select
(highlight) all the numbers that you want to make the graph of). Then hit the CHART WIZARD button on the
toolbar. (OR, you can choose INSERT>CHART on the excel menu bar)
1 – choose the XY scatter type of graph
2 – choose the ‘subtype’ of xy scatter graph that makes point only without a line on it
3 – hit next
4 – ignore the next screen (step 2), just hit next again
5 – on the next screen (step 3) .. you have to add titles to your graph. Put a title on the graph such as “Speed vs
Time for Part 1” and also label the x and y axis appropriately. Be sure to include the units (m, sec, m/s) with
the x and y axis labels.
6 – hit next
7 – ignore step four, just hit next .. this will create your graph in excel.
8 – By clicking and holding the mouse on the blank white space of your graph you can move it around the page.
You can resize the graph by first clicking on it to select it and then clicking and moving one of the small
squares on the outside border of the graph.
9 – Adding the best fit line (TRENDLINE). After the graph is made, RIGHT click on one of the data points and
select ADD TRENDLINE. Choose the type of trendline (Linear, polynomial), that best fits your data (You
can try one and then right click again to change it if it doesn’t fit well). In the same box where you choose
the trendline, you will see a tab labeled OPTIONS. Click on the options button and check the box marked
“display equation on chart”. Hit ok and your line with the equation will be displayed.
10 – Printing – To print the graph so that it fills up an entire page, first click on the graph and then hit the print
button. To print the graph so that is appears as is with all other text on the page around it you have to first
click outside of your graph and then hit the print button.
11 – Copying to Word – by simply clicking on the graph to select it and then copying it, you can easily paste it into
work and make it part of a report.
13
LAB QUESTIONS … continued
1 - Measure all angles in this shape. Be as accurate as possible, you will only be given a 1 degree margin or
error.
2 - Measure the angles between the lines drawn below (you will need to extend the lines with a ruler in order to
see where they fall on the scale on your protractor, show your line extensions).
3 - Draw two lines that are separated by an angle of 35 degrees.
14
LAB QUESTIONS
4 - Make a scale drawing of a Boat that is 25 ft long and has a sail that rises 40 ft into the air. Be sure to show the
conversions from real life measures to paper measures .. follow the steps below.
(a)
Choose a scale for your boat
State your scale factor here
(b)
[
]
Use your scale factor to convert the real life boat dimensions into paper dimensions.
Length (25 ft)
⎛
25 ft ⎜
⎝
⎞
⎟ =
⎠
⎛
40 ft ⎜
⎝
⎞
⎟ =
⎠
Height (40 ft)
Draw your scale drawing here (draw the boat). State your scale next to the drawing.
Be sure to use a Ruler to draw straight lines properly measured.
15
… continued
(c) - Measure a TV in inches. Write down what the measurements of the TV are. Then follow the same steps as
shown above to make a scale drawing of your TV.
16
More LAB Questions
5-
Use two of your fingers (not your thumb) to trace a V shape on the paper. When you trace the shape, it
will be sort of a U shape, use a ruler to turn it into a V shape. Now measure this angle
6-
Measure the dimensions of the top of your kitchen table in inches (be sure to use the inches side of a
ruler) Record these dimensions below (if your table is round, then just pretend it is a rectangle and
measure the longest center parts of the table, then draw it rectangular when you are done). If you don’t
have a kitchen table for some weird reason, then use a different table in the house.
Length ____________
Width
7-
____________
Measure parts of your body in inches
Length of your head
_____________
Length of your arm
_____________
Length of your leg
_____________
Length from your chin to waist
_____________
17
8 - Make scale drawings of the table and your body.
Be sure to indicate your scale next to your drawing. Draw your body as a stick figure. Separate each arm 60°
from your torso and separate your legs by 30° from each other
18
END OF LAB – Intentional Blank Page
19
Measurements Lab
NAME: _____________________________
Read the entire handout and
answer all “Prelab” questions
prior to lab day
20
Discussion
A large part of physics experiments involves the acquisition of data. Normal values that are measured during lab
are distance and time data. These values are then used in corresponding formulas to determine physical
quantities such as velocity.
1. Length Measurement Devices.
a.) Meter sticks
Meter sticks often have dented edges so you would not measure objects starting at the 0 mark. Begin your
measurements by starting from some other convenient point as the zero point. You would therefore have to
make a correction for this and be careful you are recording the actual distance when making measurements. For
example, if you started measuring a box at the 10 cm mark and the other end of the box fell on the 25 cm mark,
the length of the box would be 15 cm (You had to subtract 10 cm since you started at 10 cm and that is extra).
Each small little mark on the meter stick is one mm (millimeter), and the numbers listed on the stick are the cm
(centimeter). 1 cm contains 10 mm, and the whole meter stick contains 100 cm (which would be 1000 mm).
When you make a measurement with a meter stick make sure the stick is level and line up the hash marks on the
stick as accurately as you can. Your measurements should be made to 3 decimal points. For example: 1.052
m which represents 1 meter + 5 cm + 2 mm.
Example. You are measuring the length of the box shown below.
IIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIIII
10
11
12
13
14
15
The end of the box falls between the 12 and 13 cm mark. It is actually located at the 12.5 cm mark and we
started at 10 cm so the box is 2.5 cm long. We then convert this to m using our factors and we have
2.5 cm = 0.025 m
PRELAB QUESTION
1 - Use a ruler to measure the length of this line.
Measure the line in centimeters (cm) and inches (in), then convert the cm to meters (m) and the (in) to feet (ft),
show the conversion factors.
Measured Length (cm)
Measured Length (in)
Conversion to (m)
Conversion to (ft)
21
2. Volume Measurement
Regular shaped objects can have volume determined with simple measurements and math using:
(rectangle V = l x w x h, cylinder V= π r2 h).
Irregular shapes need an alternative method. The water displacement technique can be used for all objects.
This method is very simple and involves submerging an object in a tank full of a fluid and catching the fluid that
spills out. Obviously the amount of fluid displaced must equal the volume of the object put in the fluid. Also, it is
important to make sure the fluid is added to the exact point of spilling so that when you submerge the object
water will immediately come out of the tank.
Water volumes are usually given in L and ml, whereas object volumes are given in cm3 or m3.
Conveniently, it turns out that 1 ml is equivalent to 1 cm3. Therefore, if you know how many ml’s of water are
displaced, the volume of the object is the same amount stated in cm3. (ex: 24.5 ml is the same as 24.5 cm3)
HOWEVER, converting the m3 is not as simple. Beware, 1 m3 is NOT equal to 100 m3.
We have another conversion factor to work with m3. This factor is:
1L = .001 m3, or 1000mL = .001 m3. YOU WILL NEED THIS FACTOR FOR THE LAB, Don’t bother
asking how to convert mL to m3, you will be told to go away and clearly did not read the directions.
Schematic of this method
Tank – filled to capacity
Irregular Object
Catch overflow.
Overflow (to catch displaced water)
Then pour overflow into graduated cylinder.
PRELAB QUESTIONS
1 – an irregular object is placed in a tank and 5 ml of water is displaced. What is the volume of the object in cm3
and also in m3
2 – an irregular object is placed in a tank and 2 L of water is displaced. What is the volume of the object in cm3
and also in m3
3 – What types of objects would not work well in this method, explain
22
Lab Procedure:
1. Rectangular Objects
Using a meter stick, measure the length (long part), width and height of the boxes provided. Measure each
side twice, once with the “cm” side and also the “in” side of the ruler, this is the reason each
quantity is written twice, to record the two different unit measures. Put each measurement in the
table and put the unit with the number. DO NOT CONVERT ONE UNIT INTO THE OTHER MATHEMATICALLY;
RATHER BE SURE YOU ACTUALLY MEASURE TWICE, ONCE WITH THE INCHES SIDE AND ONCE WITH THE
CM SIDE.
Box #
Length
Length
Width
Width
Height
Height
1
2
3
2. Circular Objects
Using the provided materials, measure the circumference, diameter and height of the circular objects in
centimeters (this should NOT involve mathematics, only measurements). Put units on all numbers
Object
Object Description
Circumference
Diameter
Height
#1 (can1)
#2 (can2)
#3 (can3)
For the two other circular objects provided, measure only the circumference and diameter in centimeters
Object
Object Description
Circumference
Diameter
#4
#5
2. Mass measurement - Use the provided scales to measure the masses of the 3 rectangle and circular(#1-3)
objects. Mass should be in kg. Put units on all numbers
Object
23
3. Volume measurement
Use the water displacement technique to measure the volume of all the boxes and cans. Convert volumes to m3,
be sure you read the prelab. Put units on all numbers.
Object
Volume
Converted Volume
Show a sample calc of your conversion to m3
24
Analysis and Questions
1. Measurement – Conversion Factor
a. Recopy your data from lab day into the table below. Calculate the “factor” column in each section by simply
dividing the cm unit by the in unit. Also determine the average of each “factor”
Length
Box #
cm
factor
in
cm / in
Width
cm
factor
in
cm / in
Height
cm
factor
in
cm / in
1
2
3
Average
b. Calculate a single final average of the three average conversion factors from the table above, show work and
units.
c. The established conversion factor to convert “cm to in” is [1 in = 2.54 cm]. Use the final average conversion
factor found above as an experimental value and determine the percent error of our experimental value vs. the
accepted value. Show equation and work with units.
25
2. Circle Geometry – Area
a.) Calculate the area of the face of each circular object measured. Show one sample calculation below the table
Object
Diameter
Radius
Area
#1
#2
#3
#4
#5
b. Create a graph of area vs radius and plot the points for each object above. Draw a best fit line or curve to fit
these points. (Remember graphs are always described as Y vs X so this tells you which value should be on which
axis). Be sure to title the graph and label the axis with units.
c.) What kind of relationship does this graph indicate? (don’t simply say direct or indirect, give the specific type,
linear, squared, inverse, inverse squared …)
26
3. Circle Geometry – Finding Pi
Discussion - In part 2 of the procedure, we measured the circumference and the diameter of circular objects.
Circle geometry describes the value of pi as the ratio of any circles circumference / diameter and this value is a
constant that always comes out to the same number. This number has been established as pi = 3.14159
a. Based on the explanation above, use your data to calculate an experimental value of “pi” for each object. Also
calculate an average value of pi
Object
Circumference
Diameter
π
#1
#2
#3
#4
#5
Average
b. Create a graph of circumference vs diameter and plot the points for each object above. Draw a best fit
straight line to fit these points. (Remember graphs are always described as Y vs X so this tells you which value
should be on which axis). Be sure to title the graph and label the axis with units.
27
c. Find the slope of the line drawn in part (b). Show equation and calculation
d. The slope is found by dividing y axis values over x axis values (Circumference / Diameter). Based on the
“discussion” in this section of the lab, what value did you just calculate?
e. The established value of pi is (pi = 3.14159). Using the final average value of pi calculated in your chart on
the previous page, determine the percent error of our experimental value vs. the established accepted value.
Show all work including formula.
28
4.) Volume Measurement
Vcylinder = π r2 h
Vrectangle = l x w x h
I. Cylinder.
(a) Select a cylinder that you measured and rewrite the data for that cylinder here, include units.
Cylinder Type __________________________
Data:
Circumference ___________ Diameter _____________ Radius ____________ Volume _____________
(Note the volume above should be from the water displacement method)
(b) Using the formula provided, determine a mathematical value of the volume, show formula and work w/ units.
(c) Which measurement do you consider to be more accurate, explain
(d) Calculate the percent error of the calculated volume compared to the water displacement volume, and use the
one you considered to be more accurate as the accepted value. Show all work including formulas and units
29
Repeat the calculation for a rectangular object.
I. Rectangle Object
(a) Select a rectangle that you measured and rewrite the data for that rectangler here, include units.
Rectangle Type __________________________
Data:
Length ___________ Width _____________ Height ____________ Volume _____________
(Note the volume above should be from the water displacement method)
(b) Using the formula provided, determine a mathematical value of the volume, show formula and work w/ units.
(c) Which measurement do you consider to be more accurate, explain (if your reasons are the same as before
simply note this).
(d) Calculate the percent error of the calculated volume compared to the water displacement volume, and use the
one you considered to be more accurate as the accepted value. Show all work including formulas and units
30
Intentional Blank Page
31
Physics Lab
Name: ____________________
What's the Altitude
Discussion is used to do calculations, Procedure is on the Back.
Discussion
This lab will use vector techniques to find the altitude of various things. What is altitude, it’s a fancy word for
height.
Suppose you wanted to know how high the gym was. How would you go about this? Well the best way would
probably be to ask a maintenance guy, but if we wanted to measure it ourselves we would have to do something
else. We could get a very high ladder and drop a line to measure it, but there is a better way. We can use
trigonometry to measure the building height (finally a practical use for it).
See the example below.
h1
h
θ
ho
ho
L
In the example above we are looking to find the height of the building (h).
In order to do this, you can use a device to sight the top of the building as shown and measure the angle of
inclination θ from a horizontal line at your eye level. We can then measure the horizontal distance to the building
(L) and the height of our eye (ho) and use those values with trigonometry to find height h1 and ultimately height h.
Using a protractor and a hanging string, you can aim at the top of the building and read the angle we are inclined
at.
Lets do an example with real numbers. We will refer to the diagram above.
We are looking to find the height of the building (h) so we measure the distance L that we are standing away from
the building to be 100 ft. The height at our eye level is measured to be 6 feet and when we aim at the top of the
building we find the angle of inclination θ to be 20 degrees. The interior triangle would then look like this:
Using trig we can find side h1. We are looking
for the opposite side and know the adjacent
side. (opp, adj) Tan θ is the trig function with
opp and adj so we will use that one.
h1
tan θ =
θ = 20°
100 ft
opp
adj
tan 20 o =
h1
100 ft
h 1 = (tan 20 o ) ( 100 ft )
Cross multiply and then
h1 = 36.4 ft
32
We have just solved for h1 so we now have
h1 = 36.4 ft
h=?
θ=
6 ft
ho = 6 ft
L = 100 ft
Quite obviously we can now easily find the height of the building by adding the height of the altitude gun (ho) to
the height of the building from that point (h1).
h = 42.4 ft
Procedure
In this lab we will measure the height of various things using the procedures outlined in the discussion. Be sure to
measure everything you need in order to complete your calculations:
In each case, you need to measure these three things, and you have to do it two times at different distances.
(1) the height of your hand from the ground (ho)
(2) the angle of inclination (θ)
(3) how far away you are from the point you are shooting at (L).
Make two measurements of each object by using different distances (Do it twice with different “L”’s).
Make measurements and record the data necessary to find the height of the following things:
1. The flag pole in front of the school.
2. A specific tree in the courtyard … As you walk out into the courtyard from the auditorium, there is a centrally
located tree that has and obvious flat cut near the top. Measure data so get the height of this cut off part.
3. When you look at the Boys Gym from the front of the school, you will see a peaked roof that looks like
this:
Find the height of that peak measured from the ground up.
Analysis
For each object measured at each distance, draw a sketch as detailed in the “Discussion” and determine the
height of each object. 6 sketches total.
33
LAB – Forces as Vectors
NAME: _________________________________
Procedure
1.) Connect two force scales with a string and mount them on vertical support rods
2.) Attach a weight to the string, but not at the center so that each string will be inclined differently as shown.
3.) Case 1 – arrange the apparatus so that angle θ measures 90 degrees and record the force scale readings
4) Case 2 – arrange the apparatus so that angle θ measures an angle other than 90 degrees. Record your
chosen angle and the readings from the force scales
34
Questions
1.) Using graph paper, determine the resultant of your forces for each case
Attach your graph and list your answers here:
2.) Compare the difference between the weight of the hanging mass and the resultant force. Is the difference
significant or is it an indication of experimental error, give evidence to support your results.
3.) Why would you expect the resultant of the spring scales and the hanging mass weight to be approximately
equal?
4.) Why don’t the spring scale readings add up to the hanging mass weight, how do you account for the
difference (think of components)?
5.) Could the spring scale readings ever add up to less than the hanging mass weight?
6.) How would you set up the scales to make the readings add up to exactly the hanging mass weight?
35
LAB : Using A Spark Timer
Read through the whole lab
and answer prelab questions
prior to lab day.
Name: ___________________________
36
Introduction
A spark timer is used to make accurate time and distance measurements for moving objects. To put it simply, a
spark timer is like a high tech stopwatch. It is basically a small box through which a piece of special tape is
pulled through. Inside this box, a spark is made and repeats in a known amount of time. When the tape is
pulled through the box, sparks marks are made on the tape.
Sparks made here
Tape pulled through
Since we know how often a spark is made, we can count the number of marks on the tape to see how long it
took the tape to move through. A finished tape would look something like this.
● ●
●
●
●
●
●
●
●
Using the Timer
As seen above, the timer will make a series of dots and therefore also a series of “spacings” or gaps between
dots. It is these spacings that we want to focus on. The timer is set to produce these spacings at a known time
interval. The timer can be set at either 1/60 of a second (60 Hz) or 1/10 of a second (10 Hz). When set at 1/60
of a second, this means that it takes 0.0167 seconds (1/60) to make a space. A setting of 1/10 would then mean
each space is made in 0.10 seconds.
We can easily measure a spacing with a ruler to find the distance. The time for the spacing is also known (1/60
or 1/10 sec per space depending on how the timer is set). We can therefore use this data to determine the
speed at a given spacing by finding distance over time.
Sample tape analysis: The spark timer is set at 1/60 and a motorized car pulls it through. The tape is shown
below.
● ●
●
●
●
●
●
●
●
Visual Analysis: Since the dots get farther and farther apart in the beginning, we can see that the car must be
speeding up Î logically, if each dot is made in the same amount of time and the spacing between them is
getting larger, the car must go faster for this to happen. In the second half of the tape, the dot spacing is
constant and therefore we can conclude the car was moving at a steady rate (constant speed)
Note: The spacing between each dot is what we are measuring here, not the dot itself. Therefore, we want to
count the # of dot spacings to determine the amount of time for a given distance rather than counting the # of
dots by themselves.
37
● ●
●
●
●
●
●
●
●
Initial and Final (Instantaneous) speed of car:
Instantaneous speeds can be assumed to be average speeds over very short time intervals.
The initial speed of the car will simply be the speed of the first spacing which can easily be found by using the
distance and time of this spacing. Likewise, the final speed will be determined using the last spacing.
For the sample tape above:
The first spacing takes 1/60 sec to make and measures 0.5 cm (.005 m).
This gives a speed of (v = d/t = 0.005 m / (1/60) sec) = 0.3 m/s
The last spacing takes 1/60 sec to make and measures 3.5 cm (.035 m)
This gives a speed of (v = d/t = 0.035 m / (1/60) sec) = 2.1 m/s
Average Velocity of the car: The average velocity of the car is defined by the total distance traveled / total time.
Using the tape, we measure the distance from the first dot to the last dot with the ruler.
Then we can count the total number of spacings and add up to get the total time
NOTE: The time used here is not 1/60 of a second, rather it is the total time.
Measured Distance = 16.5 cm
convert to m Î total distance = 0.165 m
Total # of dot spacings = 9
x (1/60 sec) per spacing Î
total time = 0.15 sec
Avg Speed
= dist / time
= 1.1 m/s
38
Prelab question:
A toy car has a spark timer tape attached to it and moves down a track. The timer is set to the 1/10 setting.
●
●
●
●
●
●
●
●
●
●
Visually inspect the tape above and qualitatively (no numbers) explain what the tape tells you about the motion
of the car. Explain your reasoning.
Calculate the average velocity of the car, the initial instantaneous velocity of the car, and the maximum
instantaneous velocity. (show all work with all equations and units)
39
Procedure
Each person must produce and analyze their own tape. After running a tape, tape
it to the attached “timer tape collection sheet”. Cut the timer tape as necessary to
fit it on the page, but be sure to cut it at the location of an appropriate dot and
keep the tapes in order when pasting them. Fix the timer tape firmly to the
collection sheet. YOU WILL LOSE POINTS IF YOUR TAPES ARE NOT NEATLY
AFFIXED TO THE COLLECTION SHEET, ARE CRINKLED OR ARE HARD TO READ.
PART A
_____1.
Put the spark timer box flat on the lab table. On the face of the timer there is an arrow to show
the proper direction of travel of the timer tape. Set the timer to 1/10 second (10 Hz) intervals so
that each interval between dots represents this amount of time. Be sure the timer switch is off.
Plug in the timer.
_____2.
Take a roll of timer tape and note that the outside of the tape while it is on the roll is the part that
should face up when it is put in the timer. Have each person rip off a piece of timer tape
approximately 0.50 meters long. Measure 15 cm in from what you will use as the front end of the
tape and put a line across it to mark a start position.
back
start
front
15 cm
_____3.
Feed the tape through the timer (outside up) so that the 15 cm starting mark is near the front of
the spark timer as you feed it in (see diagram below). Use masking tape to attach the front end of
the spark tape to the cart as shown in the diagram below, do not tape it to the wheel.
Front
15 cm
Start line
DO NOT TURN ON THE TIMER OR START THE EXPERIMENT YET, FOLLOW DIRECTIONS EXACTLY,
The Note below is for information purposes only, it does not tell you to start yet.
NOTE: The 15 cm of space from “front” to “start line” is used as slack in this lab to get
the cart moving before you start the stop watch. YOU WILL NOT START THE TIMER
UNTIL THIS START LINE REACHES THE TIP OF THE SPARKING MECHANISM. Dots will
be created in this first 15 cm, but are not relevant are only used to get the cart going. The only
dots we will be looking at are the ones that form after we pass the start position. The first 15 cm is
only used to get the cart going and we will ignore these dots when analyzing.
_____4.
Put a 1 kg mass in the cart.
40
READ STEP 5 COMPLETELY BEFORE PROCEEDING.
_____5.
Description of task - One person is to pull and move the cart at a moderate constant speed, not
too fast and not to slow. You will be counting the spacings so if its too slow there will be too many
and if its too fast there will not be enough. When the “start line” reaches the part of the
spark timer where the dots are being made, the other person will begin timing with a
stopwatch for the rest of the pull and stop it when the tape leaves the spark timer
(Note: A stopwatch is being used to investigate the accuracy of the spark timer’s timing
mechanism, but technically a stopwatch is not needed to get the time, you could just use the dot
spacings on the tape)
Procedure
a) Turn on spark timer
b) Begin pulling car
c) Start stopwatch when “start line” on spark tape reached the spark creating location of the timer.
d) Stop the stopwatch when the spark tape comes out.
e) Turn of spark timer
Recorded Stopwatch Time: ____________________________
_____6.
Take the spark tape and use scotch tape to attach it to the collection sheets at the end of the lab.
Cut the tape when needed and continue it below the first piece taking care to make sure you know
where the start and end of the tape is. Write PART A above this tape that you attach on the sheet.
PART B - Do not use the stopwatch in this part.
_____1.
Tear off a length of timer tape about 40 cm long and thread it through the spark timer.
_____2.
Keep the timer flat on the desk and move it to the edge of the lab with the tape overhanging the
side of the table.
_____3.
Set the timer to 1/60 (60 Hz) of a second so that each interval between dots represents this
amount of time.
_____4.
Attach a 50 g weight to the end of the timer tape and place a book on the floor where the weight
will hit when it is dropped.
_____5.
Turn on the timer and drop the weight.
_____6.
Turn off the timer.
_____7.
Inspect your tape. The spark timer can sometimes skip a dot. You should look at your
tape to see that a pattern exists and that it does not appear that a dot was skipped. If
there is a big messy clump of dots at the beginning of the tape, you can discard that part of the
tape. We want to only use the part of the tape where the mass was falling freely and interference
from your hand was not causing stray dots. Call your teacher if your tape looks strange.
_____8.
Repeat the above steps so that each lab partner has his or her own tape.
_____9.
Take the spark tape and use scotch tape to attach it to the collection sheets at the end of the lab.
Cut the tape if needed and continue it below the first piece taking care to make sure you know
where the start and end of the tape is. Write PART B above this tape that you attach on the sheet.
41
Spark Timer Lab
Name: _________________
1. Remember, for Part A, the dots prior to the “start line” are irrelevant. Count the number of dot intervals
(not the # of dots, but how many spaces between dots are on the tape) and use that number of dot intervals to
find out how much time the spark timer recorded for the trip.
(Remember that the timer was set to 1/10 second intervals)
Part A – Pulled Cart
(calculated time using
the spark timer tape)
Number of Dot Intervals
Spark Tape Time
Stopwatch Time
Time Calculation: (show work and explain how you got the time)
3. Assume the tape time is the actual (accepted) value and find the percent error of times. (show formula and
work)
(For questions 4-8 refer to the introduction of this lab if you need help to perform the calculation)
4. Based on the pattern of dots shown on the tape, does it appear to have been pulled at a constant speed.
Explain your answer.
42
5.) Calculate the average speed of the pulled cart over the whole distance recorded by the spark timer. Show
work clearly, not just numbers.
6.) Calculate instantaneous speeds at 4 random locations to check whether the speed was constant or not. Label
and circle the locations you choose A,B,C,D on the tape and show you work clearly for each one.
State your conclusion based on these calculations
43
Part B – Dropped Weight
Remember for this part, if there is a clump of dots at the beginning, this should be ignored. Use the first
distinguishable dot that begins the dot pattern as the starting point.
7.) Calculate the average speed of the dropped weight over the recorded distance. Show all measurements,
calculations and data clearly including formulas and units
8.) Calculate the initial speed of the weight just after it started moving and the final speed of the weight as it hit.
(clearly show all work and steps used to calculate values, including formulas and units)
Summary Question
1.
How can the dots on a timer tape tell whether an object is speeding up, slowing down or moving constant?
44
45
Lab Investigation: Acceleration
Name: _____________________________
46
Materials
spark timer
timer tape
stop watch
cart
old books and/or bricks
ramp
Procedure
masking tape
200 g mass
DO THIS
CATCH THE CAR
WHEN IT
REACHES THE
BOTTOM.
_____7.
Set up the apparatus shown above. DO NOT tape the timer tape to the wheel. Place the spark
timer directly on the ramp behind the car. Start with a ramp height of about 10-20 cm
_____8.
Put a 200 g mass in the car.
_____9.
Rip off about 40 cm of spark tape and attach it to the car so that the outside part of tape faces up.
_____10.
Set the timer to 1/60 (60 Hz),
_____11.
Put the car at the top of the ramp, feed the spark tape in the timer and attach it to the car. Hold a
meterstick across the track in front of the car. Turn on the timer and smoothly remove the
meterstick to release the cart while your lab partner stands ready to catch it at the end of the
ramp.
_____12.
Visually inspect the tape to make sure it makes sense as sometimes the timer can skip a dot … if
you see something strange, ask your teacher to inspect it)
_____13.
Switch places and repeat so that each person has his/her own tape.
_____14.
Draw a line through the first distinguishable dot at the beginning of the tape and label this “start”.
Draw a line through a dot towards the end of the tape and label this “end”. Be sure that the start
and end marks represents points where the car was moving on the ramp unhindered. Your tape
should look something like the picture below.
START
_____15.
END
Measure the distance between the start and end lines and make a note of it.
Start-end distance ________________
Get an average value of your whole lab group
Average distance ________________
_____16.
Cut the tape at appropriate locations and fix it to the “tape timer collection sheet” provided (keep
the tape in order when taping it to the sheet).
47
_____17.
Return to the lab apparatus and remove the spark timer from the experiment.
_____18.
Put the car on the top of the ramp in the same spot that it started when using the timer tape.
_____19.
Put a piece of masking tape on the side of the ramp lined up with the front wheel of the car.
Using the average distance recorded in step 9, measure down the length of the ramp that distance
and put a second piece of tape on the side of the ramp to mark the end of that distance.
_____20.
Release the car down the ramp and use the stopwatch to record the time it takes to cover the
distance between tapes (record the time from when the car starts to when the front wheel hits
the second tape)
_____21.
Repeat the drop two more times to have a total of three trials. Measure the time with the
stopwatch each time and record it.
Trial
Time
1
2
3
48
49
Acceleration of Cart Lab
Name: __________________
PART A.) Timer Tape Measurements (ONLY USE THE TIMER TAPE FOR THIS PART)
1.) Use your timer tape to calculate the average velocity of the car over the total distance. Show and explain
work with formulas and units.
2.) Use your timer tape to calculate the instantaneous initial and final velocity of the car (this is the same as you
did in the “spark timer” lab) Show and explain work with formulas and units.
3.) Use the information in part 2 above to calculate the average velocity:
v =
vi + v f
2
.
4.) Which of the two average velocity calculations performed do you think is more accurate, explain. (Don’t make
a silly statement like ‘the formula has less variable so less error’, that makes no sense. One method is more
accurate based on how it is determined and what goes into it, not based on possibility for mistakes)
50
5.) Determine a percent error between the two calculated average velocities and use the value you consider more
accurate as the accepted value. Show formula and work with units.
6.) Using only the velocities from part 2 (vi and vf) on the previous page, and the total time of movement,
determine the acceleration of the car, show all work with formulas and units.
PART B.) Stopwatch Measurements – (use the stopwatch times as well as the distance on the ramp for this part)
1.) Find an average value of the three times recorded using the stopwatch, show work.
2.) Assume the car started from rest (vi = 0) and use the distance and time values recorded in the stopwatch part
of the lab to determine the acceleration of the car. This is just like a normal physics problem from class. List all
the known variables, pick an equation, plug in and solve.
51
3.) In part A step 6 and in part B step 2 you calculated two different accelerations, which do you think is more
accurate, explain your reasoning
4.) Determine a percent error between the two calculated accelerations and use the value you consider more
accurate as the accepted value. Show formula and work with units.
C.) Graphs
1.) Using a ruler, measure the distance on your spark tape for the dot intervals indicated in the chart and fill in
the chart. Note that the INTERVAL NUMBER: 1,2,3 … does not represent each spacing since we are
starting from dot one each time. The time and distance should be getting significantly larger for each interval.
2.) Each dot spacing on your tape represents a given amount of time based on what the spark timer is set to, as
we learned in the spark timer lab. Use this fact to calculate the times for the intervals shown in the chart below.
Be careful because each interval has a different number of spacings. The first interval is only 1 dot spacing (dot
1-2) while the second interval is 3 dot spacings (1-2, 2-3, 3-4)
Explain how the time is calculated.
Interval
Time
Distance
(1) Dot 1 Æ Dot 2
(2) Dot 1 Æ Dot 4
(3)
1Æ6
(4)
1Æ8
(5)
1 Æ 10
(6)
1 Æ 12
(7)
1 Æ 14
(8)
1 Æ 16
(9)
1 Æ 18
(10)
1 Æ 20
(11)
1 Æ 22
(12)
1 Æ 24
2.) Using a computer program, make a graph of distance vs. time and attach it to this report.
(The terminology __ vs. __ tells you which value to put on the x and y axis)
52
Questions
1.) List reasons for error in any part of this experiment. Do Not simply write “human error” or “miscalculations”
or “rounding”; those are not reasons for error. Reasons for error can include human factors, but you should
specifically state what they are rather than writing ‘human error’. Furthermore, errors are not mistakes or things
you could correct, rather they are uncontrollable and could be there no matter how many times the experiment is
conducted.
2.) The graph you created in this lab is a “d vs. t” motion curve. Based on the principles of motion curves
learned in class, what does the shape of the graph suggest about the motion of the cart. Explain your reasoning.
DO NOT SIMPLY SAY ‘as time increases distance increases’, rather analyze this graph as though it was a question
from a homework assignment on motion curves asking you to interpret what the graph tells you about what the
car is doing.
3.) In part B of the lab you calculated the acceleration of the car with the stopwatch time.
List that acceleration value here ____________________
(The following questions are just like basic kinematics word problems as we did in class, simply label all info, pick
a formula and solve)
(a) Using the value of acceleration written above, and the fact that the car started from rest, determine how fast
( in m/s) the car would be moving if it accelerated for 10 seconds, show formula and work with units.
(b) Using this same information, how long (in meters) would the ramp have to be in order to allow the car to roll
for 10 seconds, show formula and work with units.
53
54
55
Lab Investigation: Free Fall
Name: _________________________
THIS LAB IS DESIGNED TO BE A WRITEUP LAB WHERE YOU RECREATE YOUR
OWN REPORT THAT STANDS ALONE FROM THESE DIRECTIONS. YOUR REPORT
SHOULD NOT REQUIRE REFERENCING THIS DOCUMENT AND ONLY THE LAST
PAGE (SPARK TIMER COLLECTION SHEET), SHOULD BE INCLUDED WITH YOUR
FINAL REPORT
Procedure
PART A – Measuring your reaction time.
_____ 1.) Hold a ruler vertically and have your lab partner put their index finger and thumb at the 50 cm mark
ready to catch the ruler once it drops. Drop the ruler so it falls straight down and let your partner catch
it with the two fingers.
_____ 2.) Record the distance the ruler fell.
_____ 3.) Switch partners and get results for the whole group.
_____ 4.) Record everyone’s results and calculate their reaction times, show calculations. Tell the winner that
they are the coolest for being so quick.
Name
Distance
Reaction
Time
Do not calculate the times now. Do this once the lab is finished.
Show a sample calculation of how you did your work for one
person. Remember, this is a simple free fall problem that starts
from rest. Just like a problem in class, write down all known
variables, pick an equation and solve for the unknown.
56
PART B – Acceleration of Gravity.
Description of Task - Use the spark timer, tape, and weight to find an experimental value of the acceleration
due to gravity. Use about 50 cm of spark timer tape.
Procedure
_____ 1.) Set the spark timer to 60 Hz. With this setting, each dot spacing gives you 1/60 of a second.
_____ 2.) Place the spark timer so that it rests horizontally on the edge of the table and overhangs slightly
_____ 3. Attach a 50 g weight to approximately 50 cm of timer tape (does not have to be exact), and feed it
into the spark timer with the proper side facing up.
_____ 4.) Turn on the timer, drop the weight on a book so that it does not mark the floor, then turn off timer.
_____ 5.) Visually inspect the tape to make sure it makes sense as sometimes the timer can skip a dot … if you
see something strange, ask your teacher to inspect it.
_____ 6.) Get one tape for each member in the group. Make sure the dots that you are going to use represent
times when the mass was freely falling.
_____ 7.) Cut the tape at appropriate locations and attach it to the tape timer collection sheet.
- - - - - - - END OF EXPERIEMENT - - - - - - -
Lab Writeup Notes:
- Your results should be presented in a table, but you must give a
sample calculation drawn out in detail with formulas and numbers
plugged in with units for one sample of each value that is calculated in
the table.
- All measurements should be in “m” and “sec”
57
Analysis
– be sure to organize your analysis so that it is clear and easy to follow
Part A – Reaction Time.
Recreate the table with your lab partners’ names, the distance of fall and the calculated reaction times. Show
one sample calculation of how you arrived at your results.
Part B – Finding “g”
1.) Ignore the first 1 or 2 dots on the timer tape (or more if the beginning portion is hard to distinguish, ask your
teacher if you have doubts). Draw a vertical line on the first dot you will use and mark it “start”. Also draw a line
at the end of the tape on your last dot and mark it “end”.
2.) Measure and record the total distance traveled from “start” to “end” _________________________
3.) Velocity Calculations
Complete the values in the table below, put units in the top row with the labels. (Be sure to show sample
calculations where needed). Each single interval has the same time, but the elapsed time is the total sum of
intervals up to the interval you are looking at. USE METERS AND SECONDS, NOT CENTIMETERS. DO NOT PUT
FRACTIONS IN YOUR TABLE, USE DECIMAL NUMBERS.
Dot Spacing
Distance of
Interval
Time of
Interval
Instantaneous
Velocity
Total elapsed
time since start
1 (dot 1-2)
2 (dot 2-3)
3 (dot 3-4)
Continue for
all
spacings
4
58
4.) Acceleration of gravity “g”
PARTS (a), (b) and (c) below should all be done on the same page which will include your graph and
the necessary work to answer the questions. Make the graph in excel, copy it, and then paste it in
word so you can do your work below it.
(a) Make a graph of Instantaneous Velocity vs Total Time (remember what the “vs.” means). Be sure that the
time is the total elapsed time from the start to the point you are looking at and NOT the time only for that
interval you are in. Add a best fit line or curve to the graph (use excel’s trendline feature). If your best fit is a
curve (it shouldn’t be), add that trendline, however we also want to add a linear trendline as well to be used to
get an average value for the acceleration. If you have a curve, this linear line should be added by hand as a
dotted line.
(b) Using only the “v vs t” graph, determine the acceleration of the falling object using the linear trendline. Do
not use physics formulas to calculate g … we have made a V-T motion graph and we can use this to find the
acceleration just as you would on a motion curve homework assignment. DO NOT PICK POINTS and plug them
into the acceleration equation. CLEARLY SHOW YOUR WORK AND EXPLAIN HOW YOU ARE PERFORMING THESE
CALCULATIONS OR HOW YOU GET YOUR ANSWER.
This value of g, acceleration due to gravity, will serve as our experimental value for “g”.
(c) Using only the V vs T motion graph, find the total distance traveled from the start to end. Explain how you
find it and then do it. Again use only the whole graph itself and the principles of motion curves to find the
distance, DO NOT PICK POINTS from the graph and plug into acceleration equations. Be careful when you do
this part, most students make a careless mistake getting the correct value for this.
Questions
1.) List reasons for error in any part of this experiment. Do Not simply write “human error” or “miscalculations”
or “rounding”; those are not reasons for error. Reasons for error can include human factors, but you should
conducted.
2.) Find the percent error of the acceleration you calculated vs. the known accepted value of g. Show work.
3.) In part 2 of the Analysis, you measured the total distance traveled by the weight. In part 4 (c) of the Analysis
you used a motion graph to calculate the total distance traveled by the weight. Find the % error of these two
calculations and use the measured value as the accepted value.
4.) You created a “v vs t” motion graph in this lab. What does the shape of this graph suggest about the
acceleration and velocity of the falling object? Describe the behavior and describe how you used the graph to get
that information. (Answer as if you were given these motion graphs on a quiz and were asked to
describe the motion of the object).
59
60
61
Lab Investigation: Spudzooka
Introduction
In this lab, we will launch potatoes outside in the sports field and we will
record data to determine how fast the potatoes go and how high they
go. BRING YOUR JACKET if it’s cold.
A spudzooka is a device that launches potatoes into the air and sends them long distances. We will go out to the
sports field to acquire data to analyze the motion of the potato.
The spudzooka will be set to different angles and fired. We will record the time of flight of the potato for all
launches. For the first shot, we will also measure the range of the projectile to be used as a comparison when
we calculate the range at this setting.
Procedure
1.) Set the gun and record the current angle setting.
3.) Each group will be given a stopwatch. When the gun is fired, begin timing the stop watch and keep your eye
on the potato. Stop the watch when the potato hits. Record your information.
4.) For the first launch only, one member of the group will run out to the potato with a tape measure to see how
far it went.
For all other launches, record the time and make a mental note of the range for each one
Based on your observations of the 5 launches rate which one went the furthest
DATA
Launch #
Angle °
Flight Time (sec)
Measured Range (m)
1
2
3
4
5
62
NOTE: The range (dx) measured for launch 1 on lab day is used as a
comparison and should not be used for any calculations besides
percent error.
1. FOR LAUNCH #1 only, Use only the angle and time of flight to determine the muzzle velocity of the gun
(Muzzle velocity is the initial velocity of the gun, this it NOT Vx or Viy, it’s the actual Vi point upwards at the
angle). Note: we have done this problem in class, it’s a projectile launched upwards at an angle with the only
known values being the angle and time of flight. You will have to use trig to get the final answer and, you can do
this problem two ways, either by looking at the up portion of the trip or by breaking it in half.
(b) Calculate the maximum height of the projectile
(c) Calculate a theoretical (accepted) value for the range. We will later compare this to the range we measured
on lab day
63
(d) Find the percent error of the calculated range you found in step 2, vs the measured range. Show all work
with formulas and units
2. Which angle produced the largest flight time and why?
3. Based on your observations from lab day, which angle produced the largest range? Does this agree with what
projectile physics would say should be the largest range?
4. List the factors that can affect the analysis of the spudzooka data (reasons for error, there are a lot of good
ones in this lab).
64
65
LAB – Linear Equilibrium II
Procedure
1.) Setup the force board by adjusting the three spring scales until the ring is in equilibrium (at rest) at the
center. To make the trial as general as possible there should not be any 90 or 120 degree angles. Be
sure to check the zero positions on the scales before starting.
2.) Represent the forces in a vector diagram drawn to scale on graph paper.
3.) Draw any convenient x and y axis with the origin located at the point of concurrency of the forces.
4.) Resolve each of the vectors into components along each axis. Label the value of each of the components
as determined from your scale.
5.) On a separate sheet of paper calculate the values of the components using appropriate trig functions.
Compare the results to your graphical results
Questions
1.) What is the vector sum of the x-components? Explain
2.) What is the vector sum of the y-components? Explain
3.) Write a conclusion based on your results
66
67
Lab Investigation – Newtons 2nd Law
M2
M1
Introduction:
In this lab you will try to verify Newton’s 2nd law by analyzing the motion of a cart being pulled by a mass. This
investigation will lead you to develop relationships between force, mass and acceleration.
The apparatus being used is diagramed in the figure above (a cart is pulled by a mass hanging on a pulley which
provides the force to accelerate the cart).
PreLab Discussion and Setup:
The force pulling on the cart comes from the tension in the string (this should be obvious).
However, since the whole system is connected and accelerating, the tension in the string is not exactly equal to
the weight of the hanging mass M1. The hanging mass weight is actually larger than the string tension which
makes the connected system accelerate (think about it for a second, it should make sense). Though the system
is connected, if you consider the hanging mass M1 as an isolated object with its gravity force pulling down and
tension force pulling up, it should be clear that the gravity force would have to be larger than the tension to make
it accelerate.
In order to determine the acceleration of the cart or hanging mass, we have to look at the whole connected
system as if it were one object. It should be evident that both objects must accelerate the same since they are
connected
Based on that analysis, we can determine that the equation for this setup is
Fpull = Mtotal a
M1 g = (M1 + M2) a
ignoring friction.
So
a=
(M 1 )
(g)
(M 1 + M 2 )
with M1 and M2 defined in the diagram at the top.
68
Procedure:
1.) Setup the apparatus as shown in the figure on the cover of the lab
2.) Put _______ kg of mass in the cart and use ________ kg of mass for the hanging weight on the pulley.
3.) Devise a way to determine the acceleration of the cart other than the way discussed in the prelab portion of
this lab. Note that the acceleration of the cart is the same as the falling mass since they are attached. Describe
the procedure you will use to determine the acceleration here:
Part 1 – Constant Mass, Changing Force – in this part of the lab you will keep the total mass (M1 and M2) being
accelerated constant while changing the pulling force
The total mass (M1 + M2) being pulled must remain constant in this part, but we wish to vary the amount of force
pulling the system. We can accomplish this by simply moving mass from M1 to M2 or vice versa. But always
make sure the total mass (M1 + M2) is constant.
Conduct a series of trials where you change the amount of pulling Force (force at location of mass M1) acting on
the cart but leave the total mass (M1+M2) constant. It is advisable to do two trials for each setup to reduce error.
Record your results in the data table and be sure to include all relevant quantities as well as those that will be
needed to calculate the acceleration. Note: Mass M2 includes the mass of the cart plus whatever you put in it.
Though you won’t be using it to find your experimental acceleration, include the pulling force as a value in your
table. You will be making a graph using this information so a sufficient number of trials with varying force will be
needed.
A table is provided for you. The first 4 rows have been provided for you. You might not use every
row or every column. Be sure to label everything and include units.
Part 2 – Changing mass, Constant Force – in this part of the lab you will change the amount of mass M2 in the
cart (and therefore changing the total mass being accelerated), however, you will keep the pulling mass M1 the
same the whole time.
Repeat the same basic experiment but be sure to modify it to adhere to the parameters described above.
69
Part 1 – Constant Mass, Changing Force
Hanging
Mass
M1
(kg)
Cart +
Masses
M2
(kg)
Total
Mass
(M1+M2)
(kg)
Pulling
Force
(FG1)
(N)
Sample Calculations:
70
Part 2 – Changing Mass, Constant Force
Hanging
Mass
M1
(kg)
Cart +
Masses
M2
(kg)
Total
Mass
(M1+M2)
(kg)
Pulling
Force
(FG1)
(N)
71
Analysis –
Note: Any calculations in your table need to have a complete sample calculation for one set of numbers. The
sample should contain the formula used and you should fill in values and show how you get the answer that is in
the table.
1.) Your table should have all relevant data and your experimental acceleration should be calculated.
2.) Add a column on your data table for “Theoretical Acceleration”. Use the formula from the “Prelab Discussion”
to calculate the acceleration that you would expect to be applied to the cart.
3.) Calculate a percent error of your two acceleration values
4.) Create a graph of the part 1 data for Pulling force vs. the experimental acceleration and title this graph –
“PART1 – Force vs Acceleration (remember, Y vs X)”
4.) Create a graph of the part 2 data for total mass vs. the experimental acceleration and title this graph –
“PART2 – Mass vs Acceleration” (remember, Y vs X
Questions
1.) What does the graph you created in part 1 suggest about the relationship between force and acceleration
when the total mass remains constant?
2.) Is the graph you created a straight line and does this make sense (be sure to refer to the slope of this graph
and what the slope represents in this situation).
72
3.) What does the graph you created in part 2 suggest about the relationship between mass and acceleration
when the pulling force remains constant? Does this make sense?
4.) Give reasons for error in the experiment. Note: using wrong formulas, miscalculations and rounding, or a
blanket statement “human error” should NEVER be given as reasons for error. Reasons for error should be things
that are specific to this experiment that are not under your control. Error reasons can be related to human
factors but you should be specific in what these errors are and they should be uncontrollable. Think of these
errors as things that would be there even if you redid the experiment and calculations 1000 times.
73
Friction Lab
Name: ____________________________
74
Introduction
The coefficient of friction is defined as the ratio between the force needed to move an object and the normal
force. In equation form: µ = f / Fn. Normal force refers to the supporting surface force and is often equal to the
objects weight
Procedure
Part 1 – Determining coefficients of friction on a flat surface
Devise a procedure to
(a) determine the static coefficient of friction for a block sliding on a horizontal board.
(b) determine the kinetic coefficient of friction for a block on a horizontal board.
The static coefficient is determined from the force to start the object moving, and the kinetic coefficient is
determined from the force to keep the object moving at a steady speed.
Part 2 – Slipping on an inclined Board
Using the same board from part 1, place the block on the board and tilt it until the box just begins to slide.
Using a meterstick, make the proper measurements to be used to determine the angle at which slipping occurred
Part 3 – Testing factors which affect coefficient of friction
Devise experimental procedures to determine the factors which affect the static coefficient of friction.
Factors to try are:
a) weight of object
b) surface area of contact
c) type of surface object slides on
Be sure to only test one variable at a time while keeping all others constant. Use as much variety in
your measurements as possible and display your data in concise form. Use at least three different
variations of each factor.
75
Analysis Notes
Note: the main purpose of this lab is to investigate the
coefficient of friction. Be sure that in each part you are
actually looking at coefficients of friction rather than
simply friction forces.
Specific instructions are on the pages that follow, these
notes are just general notes to help reduce errors in
your writeup.
Other important notes:
MOST OF THIS LAB SHOULD BE TYPED. ONLY FBD’s and Diagrams in the Lab can be hand written
1 – There are three parts to the lab. Each part should have a clearly defined section in your lab report and
should not be blended into one lump report.
2 – Free Body diagrams should be drawn and all work should be shown to arrive at your answer
3 – Part 3 should be broken down into 3 subsections and should clearly be shown which section you are
working on. These sections are (Changing Weight, Changing Surface Area, Changing Surface Type). Do not
combine the sections into one. Each section should have its own data table showing the variations used and
the data recorded for that section as well any pertinent calculations. There should also be a conclusion in each
section as to what the results led you to believe about the coefficient of friction.
4 – The end of the lab should have a final conclusion summarizing your findings.
5 – Very Important – Based on the formulas used to find coefficients and what you know about coefficients, you
should know what the answers to most question in this lab already. You could have answered these questions
prior to doing the lab. Your lab data might contradict the results that you would expect. If your results are
contradictory to the way they should be, you must state this in each section and explain the way it should have
come out. You final lab conclusion should also state the way the results should of came out if your results were
unexpected.
76
Analysis
Note: A suggested format template is provided in the pages that follow
Part 1 – coefficient of friction on a horizontal board
Explain how you conducted the experiment to determine the coefficients. Using the data from part 1 of the
experiment, calculate the kinetic and static coefficient of friction and show your work.
Part 2 – coefficient of friction on an incline
(a) The coefficient of static friction can be found for a box on an incline based on the relationship µ = tan θ
where the angle θ is called the angle of repose (angle at which the box slips). First determine the slipping angle
from your lab and then using that angle, determine a value for u based on the above relationship
(b) Draw a FBD of the box on the incline and label all of the forces; be sure to draw components of the weight.
Use your measured values and physics formulas to calculate µ (do not use the new formula from part a).
(c) Does the formula given in part give you the same answer as part b?
(d) Compare the value of µ found using the formula in part a to the value for µ we found in part 1 of the lab
using the flat horizontal board. Explain results
Part 3 – factors that affect the coefficient of friction
Create 3 subsections on separate pages for each factor that is investigated, you should have data tables that
show all of your data and required values as well as sample calculations
You must find the coefficient of friction for each trial since that is what was being investigated in this portion of
the lab.
Each factor tested in part 3 (weight, surface area, surface type) should have its own page and its
own section in your lab report. There should be a separate table for each section each on a
separate page and with a description of how the experiment was performed to investigate this variable.
A conclusion should be made at the end of each section.
Part 4 - Final Summary
A final summary conclusion should be made at the end of the lab, it does not need to be overly wordy but should
summarize your findings.
77
Friction LAB Template – THIS TEMPLATE IS TECHNICALLY
NOT NECESSARY, IT IS PROVIDED AS A GUIDE AND IF YOU
SIMPLY FOLLOW THE DIRECTIONS ON THE PREVIOUS PAGE
YOU SHOULD BE ABLE TO COMPLETE THE WRITEUP
Typing Notes …. Press CTRL + to get a subscript
Press CTRL SHIFT + to get a superscript
-->
==>
Xsubscript
Xsuperscript
will automatically turn into an arrow Æ
will automatically turn into a big arrow Î
Drawing free hand arrows can be done using the drawing toolbar
(choose, VIEW, TOOLBARS and turn on the drawing toolbar)
Do INSERT , SYMBOL, to get µ, Δ, θ
Name:
Physics LAB #10
Due Date:
Partners:
Purpose:
Materials:
Procedure
Part 1
1.)
2.)
3.) …
Part 2
1.)
2.)
3.) …
Part 3
1.)
2.)
3.) …
78
Analysis
Part 1 – Determining uk and us on a flat surface
Procedure:
Part 1 procedure outlined on page 1
(no need to recopy it, you can just refer to it like I did here)
Measured Values
- To move at constant speed
Fpull = ______
Fpull = fk since pull at constant speed, Fnet=0 Î fk = _____
- To start moving
Fpull = ______
Fpull = fs(max) since just at slipping point Fnet ~ 0 Î fs(max) = ___
FBD (by hand if you like)
Fnet(y) = ma(y)
Fn = ?
µk = fx / Fn
µk =
µs
CIRCLE OR BOX YOUR ANSWERS.
repeat above math procedure to get µs value
79
(ON A NEW PAGE)
Part 2 – Slipping on an incline
Given Info
Total Mass = _______
(M)
Calculation of θ
Show how you get theta using your recorded info
θ = ______
PART 2A - Using the new given relationship to find a Theoretical Value of µs
µs = tan θ
µs = tan (___)
µs = _____
plug in your value of θ and do tan ( __ ) on a calculator to get us
PART 2B – Deriving µs using newtons laws
Draw incline and draw FBD of box on incline.
Do Fnet(X) and Fnet(y) and end up by solving for us just like you would in a HW problem. Make it neat and
organized. Note you can use the mass and angle found at the top of the page in your Fnet formulas to get your
answer.
List your answer
us =
Part C – Conclusion1
Answer the question from the analysis comparing answers 2A and 2B above
Part D – Conclusion 2
Answer the question from the analysis comparing µs found from part 1 on the flat surface to either of the µs
found in this section on the incline
80
Part 3 – Analysis of factors that affect the coefficient of friction
(SHOULD BE ON ITS OWN PAGE)
Section A – Investigation of weight changes on coefficient of static friction
Procedure – (outlined on page 1 of lab)
Surface used – board
Surface area used – large flat side of block
Weight varied
Mass (kg)
FG (N)
FN (N)
fs (N) *
us
Fill in data
table with your
values
* fs = was measured using the force scale. Since the object was moved at a constant speed, the force of pull is
equal to the fs
Sample Calculation: show only 1 sample calculation of Fg, Fn, and uk from the data above, the rest of the
calculations for the other trials should not be shown and are redundant
Conclusion:
Refer to your data table and make a conclusion about how the weight affects µs
Explain what your data shows but also state if you feel your data is a mistake and explain why.
Things to think about
us is simply a measure or surface roughness,
A heaver object will increase the amount of friction force fs acting on an object
A heavier object will increase the normal force, Fn , acting on an object
us = fs / FN
81
- NEW PAGE –
(COPY SECTION A AND PASTE IT HERE AND MODIFY IT)
Section B – Investigation of surface area changes on coefficient of kinetic friction
Should be similar to part A with some change to reflect the difference in this part – the table needs to be
modified since the mass is now constant but the surface area will be changed so that needs to be incorporated
into this new section. make sure its on a new page
- NEW PAGE –
Section C – Investigation of surface type changes on coefficient of kinetic friction
Repeat similar section analysis with modifications that involve surface type being varied
Final Conclusion:
Summarize your conclusions from these last three parts, state which factors affect the coefficient of friction and
how it was suppose to turn out …
82
83
Laboratory Investigation
Abstract: - Analysis of the circular motion of a swinging stopper will provide insight into the causes of
centripetal force and develop relationships between speed, radius and centripetal force.
Name: ___________________________________________
84
Procedure:
1. Measure the mass of the rubber stopper using a scale and record in the attached data table.
2. Attach 200 g of mass to the bottom of the string that passes through the tube. Refer to the diagram to
understand how to measure the radius. Before swinging the stopper, measure the radius so that it will be
somewhere between 50-60 cm and record this value.
RADIUS USED: _______
3. Put an alligator clip on the string just underneath the bottom of the tube and wrap the string once around one
side of the clip teeth so that the clip will not slide if pushed (see diagram).
PART 1 - Changing Mass - READ UP TO STEP 5, BEFORE BEGINNING
Practice swinging
Hold the apparatus as shown in the picture and use your
free hand to hold the weight hanging below the tube.
Begin swinging in short horizontal circles to make the
stopper go in a horizontal circle around your head.
Once you get it moving, slowly release the weight in your
hand until it hangs freely.
Place
alligator clip
Vary the speed at which you swing the stopper until you
can get the alligator clip to be just below the bottom of
the tube without it touching the tube.
Keep the swing constant so that the alligator clip
remains in place and does not move up or down.
4. In this part of the lab we will be varying the mass hanging on the rope. Choose a starting mass of either 100
or 200 grams. If you are able to swing the mass successfully with the 100 gram weight, then start with that
mass, however, if the stopper is too heavy and it is difficult to swing with such a small weight then start with
the 200 gram mass.
5. We will now take data while spinning the stopper, please read the recommendations that follow, don’t be
lazy. Sometimes the stopper will be swinging quickly so be careful when you are counting the revolutions.
The person swinging the stopper usually has the best idea about the numbers of revolutions and you can
even hear the swirling noise of the stopper to help you count. The person doing the swinging can begin
counting aloud from 1 – 27, and the person timing can start the stopwatch when they hear 5, and then stop at
25 so there will be a more accurate result of the beginning and end of the 20 revolutions. Use whatever
method is best for your lab group for counting and timing. Record your data in the attached data table.
Make sure the stopper is spinning at a constant rate in a horizontal circle and the alligator clip remains at
the same spot (just below the tube but not touching), and record the amount of time required to make 20
revolutions of the stopper.
6. Repeat step 5 one more time so that you will have two trials total.
7. Add an additional 100 g of mass hanging to string to increase the total mass
Repeat the two swing trials again and record your times on the data table.
8. Add another 100 g of mass (200 g total additional added)
9. Add a final additional 100g of mass (300 g total additional added)
85
PART 2 - Changing Radius
1. Copy the data from the first row of “part 1” table and make an exact copy in the first row of “part 2” data table.
2. For rows 2-4 in the part 2 table, use the initial amount of hanging mass on the string as you did in part 1, and
do not add or remove mass for any part. In this part of the lab we will vary the radius at which the stopper spins
around.
3. Move the alligator clip 10 cm up or down the rope from its current location (this will make a different radius
when the string is swung). Again wrap the string around one of the alligator teeth so that it will not slide if pushed.
Record the value of the new radius in your table.
4. Repeat the experiment as conducted before so that the clip is just barely below the glass tube and does not
move. Get the time to make 20 revolutions. Repeat this step 1 more times for a total of 2 trials.
3. Move the alligator clip to another different location (10 cm different than other trials) and record it. Measure
and record the time for 20 revolutions. Repeat this step 1 more time for a total of 2 trials.
4. Again, move the alligator to a new location (10 cm different from other trials) and record the time for 20
revolutions. Repeat this step 1 more time for a total of 2 trials.
------------------------------------ END OF EXPERIMENT -------------------------------------------------
86
Analysis Instructions
A common mistake in this lab is misunderstanding which mass to use. There are two masses, the hanging
mass (the one hanging below the circle attached to the string) and the mass of the stopper. Each mass is used
for a different thing in the analysis. Keep in mind that the stopper is the thing that is going in the circle, so when
using circular motion analysis it is the stopper mass that is being accelerated.
Complete the calculations on the data worksheet. Read the directions below to assist you.
(a) Hanging mass weight and Fc
Why does the spinning stopper maintain its circular motion in this lab? The stopper goes in a circle because
a centripetal force allows it to happen. A centripetal force is always provided by something. In this case the
string tension provides the centripetal force. However, if there was no mass attached to the string then the
stopper would just fly away and the hanging mass creates the tension which provides the centripetal force, so
in essence the weight of the hanging mass provides the centripetal force acting on the stopper. (note,
if you are one of the few people that actually read directions, this paragraph is the basis for the answer to one
of the questions, congratulations.)
This important relationship directly gives us Fc. Now that we know the Fc we can calculate other values.
(b) Speed (V)
We are going to find the speed of the stopper with two methods and compare the results. For the purposes of
percent error, we will assume that Method 1 is the experimental value and Method 2 is the actual value.
Method 1 (experimental V) - find the speed using distance and time.
In lab we found the time needed for 20 revolutions which we can easily use to find the Period. (Period =time
needed to make 1 revolution)
We also know the distance traveled in 1 revolution. The stopper swings in a circular path and we know the
radius of this circle. The distance traveled in 1 revolution around a circle is the circles circumference C = 2 π r
With the distance and time traveled, we can find the speed of the stopper in the circle. This is method 1.
Method 2 (actual V) - find speed using the known centripetal force
In accordance with the discussion in part (a) of this analysis we know the centripetal force on the stopper. We
also know the mass of the stopper and radius of the swing. Given the formula for centripetal force:
Fnet(c) = m ac
Fnet(c) =
mv 2
r
We can see that the only unknown left in the equation is v so we can rearrange the equation to solve for v.
Read the note at the top of this page again to be sure to use the correct values.
(c) Find the percent error for the two methods of v
Graphs - Attach
1. Make a graph of centripetal force vs. speed(method 1) for part 1 of the lab
( y vs. x )
2. Make a graph of speed(method 1) vs. radius for part 2 of the lab
( y vs. x )
87
Centripetal Force Lab
Name: __________________
When turning in the lab, only turn in from this page forward. The prior pages are for your reference only
Data and Calculations Table
ALL MASSES SHOULD BE CONVERTED TO kg
Part 1 - Constant Radius, Changing Mass
shaded columns = data to record during lab
Time for 20 revs
(s)
Hanging
Mass (kg)
Weight of
Hanging
mass (N)
Radius
(m)
Mass of
Stopper
(kg)
Trial 1
Trial 2
Average
Time
Time
for 20
for 1
revs
rev (s)
(s)
Fc (N)
V
Method 1
(m/s)
V
Method 2
(m/s)
% error
V
Fc (N)
V
Method 1
(m/s)
V
Method 2
(m/s)
% error
V
Part 2 - Constant Mass, Changing Radius
Time for 20 revs
(s)
Hanging
Mass (kg)
Weight of
Hanging
mass (N)
Radius
(m)
Mass of
Stopper
(kg)
Trial 1
Trial 2
Average
Time
Time
for 20
for 1
revs
rev (s)
(s)
88
Questions
1.) List reasons for error in any part of this experiment. Do Not simply write “human error” or “miscalculations” or
“rounding”; those are not reasons for error. Reasons for error can include human factors, but you should
conducted.
2.) Explain how you found the Fc acting on the stopper and why this is the correct way of calculating it.
3.) What does graph 1 suggest about the relationship between speed and centripetal force? Does this make
sense, explain? (you must refer a physics formula)
4.) What does graph 2 suggest about the relationship between speed and radius? Does this make sense,
explain? (you must refer to a physics formula)
5.) Which method of solving for v do you think is more accurate and why (Don’t refer to one formula being harder
than the other, accuracy should be based on the values used to find answer, not the actual formulas themselves)
89
Lab Investigation: Measuring Power
Name: _____________________________
90
Introduction
The purpose of the following exercise is to measure the power you develop while first walking,
and second, running up a flight of stairs.
Power (P) = Work (W)/time (t) and W= F•d, where in the case of doing work against gravity the force used in
doing the work must be at least equal to the weight of what is being lifted
Procedure
1.)
2.)
3.)
4.)
5.)
Using the available scale, determine your weight
Now, using a stopwatch, walk up a flight of stairs and record the time it takes. Do two trials.
Using a meter stick, measure the total vertical distance you walked.
Repeat the same procedure, but run instead of walking. Do two trials
Record values for other members in the group.
Calculations:
Separate your analysis into two separate sections, one walking section and one running section. For each section
calculate the following:
1) Convert weights in lbs to kg (1 kg = 2.2 lbs)
2) Average the two time trials for each person
3) Calculate the work done by each person
4) Calculate the power of each person in Watts
5) Convert the power to kilowatts.
91
Report
Walking
Person
Time 1
(sec)
Time 2
(sec)
Avg
Time
(sec)
Weight
(lbs)
Mass
(kg)
Weight
(N)
Distance
(m)
Work
(J)
Power
(W)
Power
(kW)
Averages ____________________________________________________________________________________
Running
Person
Time 1
(sec)
Time 2
(sec)
Avg
Time
(sec)
Weight
(lbs)
Mass
(kg)
Weight
(N)
Distance
(m)
Work
(J)
Power
(W)
Power
(kW)
Averages ____________________________________________________________________________________
92
Questions: (show all work for calculation based questions)
1. How does the power you develop change when you run up the steps instead of walking, explain why your
answer is the way it is.
2. Examine other people’s data. What type of person seems to develop the greatest power? Did anyone reach
1 horsepower (look up the conversion if you don’t know it)
Questions 3-5 use the following information
3500 Kcal is equivalent to 1.47x107 J
3500 Kcal = 1.47x107 J
3500 Kcal expended results in 1 lb (fat) burned
or
1.47x107 J expended results in 1 lb (fat) burned
1 lb = 3500 Kcal
1 lb = 1.47x107 J
Your answers must be given by actually showing conversions from one value for another by using the above
factors and the factor label method
Recall from beginning of year, to convert ft to cm
(100 ft ) (12 in) (2.54 cm) = 3048 in
(1 ft)
(1 in)
So when answering the questions you should use a similar method only with the new factors and factors you can
make from your data table.
3. Determine how many times the average person would have to run up the steps to lose 1 pound of body fat.
The factors have been setup for you. Use your data table and the proper factors from above to fill in and get the
final answer of stair runs per lb.
( ________ J )
( 1 stair flight run )
x
=
( ________ lb )
( ________ J )
93
3500 Kcal
1 lb
1 lb
= 1.47x107 J
= 3500 Kcal
= 1.47x107 J
4. How many Kilocalories do you estimate the average person expends in one hour of stair running? (The
question is asking you to convert 1 hr of stair runs into kilocalories of energy
( _____ runs ) ( ____ sec ) ( ____ J ) ( ____ Kcal )
x
x
x
( _____ sec ) ( ____ hr ) ( ____ run ) ( ____
J)
cancel the units above in the proper manner
Answer with unit
Kcal burned per 1 hr of stair running
_____________
5. Use the answer to question #4, and the same factor method, determine how much body fat is burned in 1
hour of stair climbing.
94
95
Spring LAB
Hooke’s Law & Potential energy
Introduction
In this lab you will investigate the force and stretch in a variety of springs as well as investigate energy.
Procedure
Part 1 – Collecting data to determine the spring constant (see included table within lab)
DO NOT USE THE 1 kg mass, you will break the springs and rubber bands
For each spring and rubber band provided, (data table attached)
-
Hang the spring on a clamp and measure the initial length of the spring. (note: for the rubber band you will
have to put a small insignificant amount of weight on it to get the relaxed length, you can ignore this tiny
amount of weight in the analysis)
Attach different masses to the spring and measure the final length of the stretched spring. (Place a proper
amounts of mass on the spring so that the stretch is measurable and each trial is noticeably different)
Calculate the change in length for each mass.
Use at least 5 different masses for a given spring and repeat the process for each spring or elastic band
that is provided. You DO NOT, and probably SHOULD NOT use the same 5 masses for each spring. Make
a separate table of information for each spring.
96
Part 2 – Energy Investigation
-
Choose one of the springs used in Part 1 and
select a mass that provided a noticeable stretch
to the spring but not so drastic that it will not be
able to be stretched further
Record the mass you will use and describe
which spring you chose to use
____________________________________
____________________________________
____________________________________
____________________________________
-
We will use the provided rings to setup the
apparatus show in the diagram, follow the steps
below:
-
Attach the mass to the spring.
-
Hold the mass so that the spring does not
stretch but will be at its relaxed length.
-
Move the top ring so that it will mark the
location of the bottom of the mass while you are
holding it at its relaxed position
READ THE WHOLE STEP BEFORE DOING IT
- DROP the mass from the relaxed length so that
it falls down and stretches the spring. Watch it
as if falls and make a note of where it
momentarily stops at the lowest position before
it bounces back up. Slide the lower ring up and
down on the stand to mark this lowest position.
REPEAT this drop a series of times until you
have accurately marked the lowest position of
the mass. THE LOWER RING SHOULD BE AT A
LOCATION BELOW THE MASS WHEN IT HAS
FINISHED BOUNCING.
-
Measure the length between the rings to get a value for the maximum stretch (change in length) of the
spring and record that value
________________________________
97
Analysis
Part 1
1.) For one of your springs and masses, draw a FBD of the spring at its relaxed length and next to it draw a
second FBD when the mass was attached to the spring. Label the lengths and the change in length as well as
the forces acting when the mass is attached to the spring
98
2.) Collect your data in the table below and determine the weight ( = spring force)
Rubber Band
Mass
(kg)
FSP = FG
(N)
Initial L (xo)
(m)
Final L (x)
(m)
Δx
(m)
Spring 1 – Describe Spring Here __________________________
Mass
(kg)
FSP = FG
(N)
Initial L (xo)
(m)
Final L (x)
(m)
Δx
(m)
Mass
(kg)
FSP = FG
(N)
Initial L (xo)
(m)
Final L (x)
(m)
Δx
(m)
Mass
(kg)
FSP = FG
(N)
Initial L (xo)
(m)
Final L (x)
(m)
Δx
(m)
99
3.) Make a XY scatter Graph of Force vs. Stretch for each spring and/or rubber band and be sure title each one
with the type of object used as well as the variables force and stretch (Note: you should remember how to tell
which one is the y value based on the “vs” terminology, look it up if you forgot). MAKE A SEPARATE GRAPH
FOR EACH SPRING. Be sure to put a best fit line or curve on the graph. NOTE: if the best fit is a curve, which
it probably will be for some of them, put this best fit curve in, and then after you print the graph, draw a linear
straight line to represent a representation of the average slope of the graph if the relationship were linear. This
is very important and is what you will use to find the spring constant for a graph that is naturally curved and not
linear. Some of your data might be naturally linear and not have this problem. Make the graph sized half of
a piece of paper. You can copy and paste the graph from excel into word in order to do this.
4.) Below each graph, use the graph to graphically find a value of the spring constant for each item (Note: DO
NOT PICK POINTS from the graph and plug into F=kx, and don’t average individual k values either.
Rather you should use the whole graph and realize how to use the y and x values to get the spring
constant as described in step 3).
5.) Below each graph, state whether or not the spring constant is actually constant for the spring or shows
variation based on the stretch and explain how you make this conclusion.
Part 2
The diagram below represents the motion of the spring in Part 2 of the lab. It started at rest at position A and
then was dropped until it stretched and reached position B where it momentarily stopped again.
(starting position)
\
/
\
A
hA
\
/
\
/
\
For this part of the analysis, we are going to assume that when
the spring reached position B, the max stretch, it was at a height
of zero h = 0
B (Max stretch)
(a) What kind of PE would the system posses at point A, calculate it
(b) What kind of PE would the system posses of point B, calculate it
(c) How should the results to parts (a) and (b) compare to each other. Explain in detail why they should be this
way and comment on how your results compare to what you would expect.
100
101
Name:
Static Electricity Lab
Introduction: Static Electricity Investigation Lab
Part A - Polarity test (+ or -)
Materials Provided
- Pith ball (small Styrofoam ball with a conductive coating allowing it to be charged)
- Rubber Rod
- Glass Rod
- Cotton Felt
- Silk
- Rabbit Fur
- Clear Acetate strip
- White Vinyl strip
Definitions:
(1) A rubber rod rubbed with fur or wool acquires a negative charge
(2) Like charges repel and opposites attract
Procedure:
1.) Using only the definitions and materials provided above. Devise a test to determine the type of charge on an
object and explain how your test will work. (The use of the pith ball is necessary every time and is the
main object to help in your test)
2.) Use your test to determine the sign (+/-) of the materials below
(a) Vinyl strip (white) rubbed with fur
(b) The fur from (a)
(c) Acetate strip (clear) rubbed with cotton felt
(d) Glass rod rubbed with silk
(e) A pen stroked on your hair.
Part B - Attraction or Repulsion
102
(a) Use your results from PART A (Polarity test) of this lab to positively charge an object. Charge the pith ball
positively by contact. Bring a negative charge near it and then a positive charge but do not allow the charge to
touch the ball. Describe and explain the results?
(b) Discharge the pith ball completely by holding it in your hand and letting your body act as a ground. In terms
of movement of electrons, explain what happened when you touched the ball.
- Bring a negative charge near the neutral pith ball but don’t let it touch.
- Bring a positive charge near the neutral pith ball but don’t let it touch.
What results do you observe? Why does this happen?
(c) Based on the results above, which is better proof of a charged object, attraction or repulsion? Explain by
using your results from (a) and (b)
103
Part C – Using an Electroscope
Note: When charging the electroscope by contact, it helps to rub the charged rod back and forth on the top plate
(a) Use the rubber rod and rabbit fur to negatively charge an electroscope by contact. Explain the electron flow
between the three objects (fur, rod, electroscope) that allows the electroscope to become charged
(b) Use your results from PART A (Polarity test) of this lab to positively charge an object. Bring the positively
charged object, near but not touching the negatively charged electroscope. Record your observations and
explain what you observe.
Part D – Charging by Induction
(a) Discharge the electroscope completely by using your body as a ground. Bring a charged negative rod near
but not touching the electroscope. By not touching the electroscope, no charges will be transferred from the rod.
Describe and explain the results in terms of electron flow?
(b) Move the rod away. What does the position of the pin indicate about the charge on the electroscope and why
does this happen?
104
(c) READ THE WHOLE STEP BEFORE PROCEEDING. Bring the charged rod near again. While it is near one side
of the electroscope touch the other side with your finger. Keep your finger on it and the rod nearby. Remove
your finger from the scope first, and then remove the rod. You have now induced a charge on the scope and
should see deflection of the needle.
(d) Perform a test to determine the polarity (charge) of the electroscope. Describe what happened when you
performed this test and why this showed you what sign the charge on the electroscope was?
(e) In step C the electroscope was charged by induction. Create diagrams of each step in this process and
explain what is happening in each step in terms of electron flow.
105
Introduction to Electronic Components.
Name: __________________________________________________
Notes for teacher:
Very important to tell student to not crank up the power supply and to use the ammeter carefully.
For ammeter usage.
Tell the students how to set it and what scale to use for each measurement being taken, otherwise the
fuse on the Ammeter will blow.
Emphasize verbally how important this is.
100 Ohm and higher resistors
– use the 20 or 200 mA setting.
Smaller resistors, make sure they use the higher 10A setting and don’t use the mA setting or, pop goes
the ammeter when the voltage is turned up
The only way they will actually read this lab is if you give them a quiz on it before hand.
106
INTRODUCTION
This lab will familiarize you with some of the basic components and measuring devices used in electronics.
The main components that we will focus on are:
Wires – Metal wire conductors with different end clips are used to connect components together and allow
current to flow
Resistor - an electrical component that limits or regulates the flow of electrical current
Power Supply – a device that supplies electrical energy to external electrical components
(like a battery with a plug)
Ammeter – a device used to measure the current flowing though any electrical component
Voltmeter – a device used to measure the potential difference or voltage used by electrical components
Multimeter – A device that has both capabilities of an Ammeter and Voltmeter.
107
Wires
- Wires have two types of connections on the end.
A Banana Plug
or
an Alligator Clip
The Alligator clip can be clipped directly to any exposed wire or metal
The Banana Plug is designed to be connected to a female jack as shown below.
However, the alligator clip can also be used with this jack by either unscrewing the
jack cover to expose the metal behind it and clipping the alligator clip directly to that
post, or by opening the alligator clip and inserting one side of the clip into the post
hole directly
Banana plugs can also be connected to one another by either plugging them in front to back or using the hole on
the side
Remember all connections are metal, so any way of fastening them together will allow current to flow.
108
Resistors
Resistors basically look like this:
They are like specially made wires to resist flow. To connect a resistor, use an alligator clip to directly attach to
each wire coming out of the resistor
Power Supply
The power supply is where the energy for the electrical components comes from. It can simply be a battery but
often is a more versatile unit like the one shown below. The power supply can provide a source of either DC or
AC current but we always want to use the DC side of the unit. Is should be labeled as DC.
This is a basic power supply
On the supply, there is a Knob
used to change to amount of
voltage that the supply is creating
There are also Female jacks
that banana plugs can be
connected to in order to run
wires to other electrical components.
Or alligator clips can be used as well
as described in the “wires” section of
this document
Unfortunately, the voltage that the power supply puts out is variable and will change depending on what devices
are hooked up to it or how they heat up. It is important to realize that when you turn the knob to set a specific
voltage, that will only be true for the existing setup and should be checked periodically as it has a tendency to
change. When adding or removing new devices, you must reset the voltage as it will definitely change.
When plugging into the power supply, always make sure you plug into the DC side.
WARNING
Be aware that some power supplies generate a lot of current and can damage connected components if not used
properly
(a) You should be cautious turning up the power and go slowly. Always ask your teacher if you are not getting
good readings.
(b) Never leave the power on for a long time, turn it on, take a reading and then turn it off.
109
Meters
Individual Ammeters and Voltmeters look like this
and are used to measure current or voltage
Multimeters can be both Ammeters or Voltmeters. Your teacher may choose to use individual meters for a lab, or
to use a multimeter to take all readings. The multimeter must be set a specific way to work properly and WILL
BE DESTROYED if you don’t hook it up properly.
A Multimeter looks like this …
or like this
Both types of meters can be either Ammeters or Voltmeters based on how they are connected and set.
Notice that there are 3 or more holes to plug wires into on the Multimeter. The hole labeled “COM” is used for
both Ammeter or Voltmeter connections. The other holes vary based on how you are using them … this will be
discussed in class as it can be confusing.
PLEASE TURN OFF YOUR MULTIMETER WHEN YOU ARE DONE WITH IT, it runs on batteries and they need to be
replaced when left on for hours.
IT IS VERY IMPORTANT THAT YOU KNOW HOW TO USE THEM
PROPERLY, YOU WILL DESTROY THEM IF THEY ARE HOOKED UP
WRONG
110
Using the meters to make measurements
Voltmeter (for voltage)
When using the meter as a voltmeter, it must be inserted “around” the device (each hole is connected to one side
of the device). This is called a parallel connection. If your device is already connected to a power supply or
other devices, you do not need to disconnect them as you can simply clip or touch the wires from the voltmeter
to either side of the device
Sample connection – DIAGRAM 1
Voltmeter
Voltmeter is connected to
each side of the resistor
Power
Supply
Resistor
Ammeter (for current)
When using the meter as an ammeter, it must be inserted next to (before or after) whatever device is being
measured. This is called a series connection. If your devices are already connected to the power supply or other
devices, you must disconnect them and insert the ammeter before or after it.
Sample connection – DIAGRAM 2
Ammeter
Ammeter is connected
before it goes to the resistor
Power
Supply
Resistor
WARNING
- The devices MUST be hooked up in this manner. MAKE SURE YOU
HAVE SET THE DEVICE TO VOLTMETER operation when it is being
connected as above and vice versa for Ammeter. Connecting a meter in
an improper fashion can damage or completely destroy the power
supply, wires, and the meter itself
111
Electronics Intro Lab
Name: __________________
Procedure
RESISTOR I – High Ohm Resistor, producing low currents
1.) (a) Using the wires, power supply, a multimeter setup for voltmeter setting, and the high ohm provided
resistor, connect them as shown in DIAGRAM 1 on the previous page of this Lab. Be sure to connect the
voltmeter holes as instructed by your super smart teacher and set the dial to the proper DC voltage setting.
Read the next step before turning on the power.
(b) Turn on the power supply, and slowly turn up the power slightly to get a random reading of voltage
somewhere between 1-2 volts.
NOTE: DO NOT TOUCH THE KNOB ON THE POWER SUPPLY AFTER YOU HAVE SET IT
TO A SPECIFIC VOLTAGE. Simply unplug the power supply when not taking readings, but leave the knob
where it is so its voltage setting will stay where you originally set it.
Record the voltage measurement here, with proper units
____________
unplug power supply.
(c) Remove the voltmeter from the resistor, but REMEMBER – YOU SHOULD STILL NOT TOUCH THE KNOB
ON THE POWER SUPPLY, LEAVE IT WHERE IT IS AND SIMPLY UNPLUG IT AS YOU WILL NEED IT TO
BE THE SAME IN THE NEXT STEP.
2.) (a) Using the wires, power supply, a multimeter set for the ammeter setting, and the same resistor as above,
connect them together as shown in DIAGRAM 2 on the previous page of this Lab. Be sure to connect the
ammeter holes with the milliamp (mA) setting as instructed by your omnipotent teacher and set the dial to the
proper setting.
MAKE SURE YOUR AMMETER IS SET PROPERLY TO THE CORRECT
SCALE AND THE CORRECT HOLES, YOU WILL DAMAGE IT IF IT’S
WRONG, ASK IF YOU ARE UNSURE. IF YOU DAMAGE THE METER YOU
AUTOMATICALLY FAIL THE LAB.
(b) Plug the power supply in again, and don’t touch the knob so we keep the same voltage.
Record the meters measure of current, with proper units
still do not touch the knob on it
____________ unplug power supply and
- As instructed by your teacher, the ammeter has different “scales” for its setting.
Which scale did you use for this reading
____________
3.) Use OHMS LAW ( V = I R ), and the measurements above to calculate the resistance of the resistor. Show
work.
112
4.) - Using two multimeters, one setup as an ammeter, and one setup as a voltmeter, connect the devices as a
combination of DIAGRAMS 1 and 2, so that both the ammeter and voltmeter are connected at the same time.
The alligator clips can be clipped onto each other since they are metal and any physical connection will allow
current to flow.
IF YOU ARE UNSURE OF YOUR CONNECTIONS, ASK YOUR TEACHER TO LOOK AT IT. A WRONG TYPE
OF CONNECTION CAN CAUSE DAMAGE TO THE DEVICES, BETTER SAFE THAN SORRY.
- Plug in the power supply and observe the results. You should have the same readings that you did before
except you can get them both at the same time.
- Now we will adjust the power supply with the knob: note that this is the first time in the lab when you should
be changing the knob from its initial setting. Turn up the power supply slightly, but keep it less than 3 volts and
turn it off once you observe different readings. As the voltage increases, what happens to the current, give a few
examples?
5.) With the same setup you made above, move the knob on the power supply the set a new voltage less than 2
volts and different that the voltage used earlier. Record it below as well as the current. Then, leave the power
supply set to this voltage and unplug it, but do not adjust the knob after you have set the voltage.
Calculate the resistance again with these new values. Show your work and comment on the result.
Voltage __________
Current __________
113
6.) Resistor II – Low ohm resistor, producing higher currents.
(a) Once again, leave the knob on the power supply alone. Replace the resistor with the second low ohm resistor
that you were given.
(b) You will have to change the scale on the Ammeter to the high setting now as instructed by your teacher.
MAKE SURE YOUR AMMETER IS SET PROPERLY TO THE CORRECT
SCALE AND THE CORRECT HOLES, YOU WILL DAMAGE IT IF IT’S
WRONG, ASK IF YOU ARE UNSURE. IF YOU DAMAGE THE METER YOU
AUTOMATICALLY FAIL THE LAB. Remove the plugs in the holes on the Ammeter and connect
them to the proper locations and turn the dial to set the proper scale. MAKE SURE YOU HAVE ADJUSTED
THE SCALE AS INSTRUCTED BY YOUR TEACHER OR YOU COULD DAMAGE THE METER
Which scale are we using for this part ____________
(c) Plug in the power supply.
What is the voltage reading with this resistor (resistor 2) ?
(Resistor 2) V = ____________
What was the voltage reading with resistor 1 in the prior setup?
(from step 5 on the last page)
(Resistor 1) V = ____________
NOTE that this voltage (for R2) is different than it was with the other resistor (R1) even though you never
touched the knob. This is an important thing to learn about power supplies. The voltage they put out is based
on what is connected to them. If you change anything in the setup the voltage at the given knob setting will
change, so you must always take new readings and make adjustments when making changes to a setup. They
can even change when left on too high or too long as things get hot. Adjust the knob so that the voltage returns
to its initially setting to match what was applied to resistor 1, record that value here (its obvious what this should
be, we are just checking to see if you are reading these directions).
(Resistor 2) V = ____________________
(d) Record the current from the ammeter in the space below, and use the voltage and current to calculate the
resistance of the resistor
114
115
Lab Investigation:
Resistance and Ohm’s Law Investigation
Notes for teacher:
White Bulbs – Use 40 and 60 W
bulbs to keep currents relatively
low but to still allow expected
results.
Bulbs – clear and white – use
mA setting.
NAME: ______________________________________
Thin Nichrome wire – VERY
VERY IMPORATANT to use the
high current max setting, using
a low mA setting will destroy
the ammeter.
116
Introduction:
1.) In this lab, we will investigate how the length of a wire affects resistance and the relationship between
current, potential and resistance. We will also investigate how changing voltages effect resistance and current in
wires and light bulbs.
THE POWER SUPPLY SHOULD ONLY BE TURNED
ON FOR BRIEF PERIODS OF TIME WHEN BEING
USED. TURN IT ON, TAKE A READING, THEN
TURN IT OFF OR UNPLUG IT. LEAVING IT ON
WILL CAUSE BURNING
2.) We will be using Ammeters and Voltmeters in this lab. IT IS VERY IMPORTANT THAT YOU KNOW HOW TO
HOOK THEM UP. If hooked up wrong you will destroy the meter. ASK YOUR TEACHER is you are unsure if
it is hooked up properly. This is especially important when using the Ammeter.
SETTINGS TO USE FOR THIS LAB – ** VERY VERY IMPORTANT TO FOLLOW
THIS
Part A – Wire Length Investigation
Ammeter Scale – use the high scale setting and make sure the plugs are attached to the correct jacks.
Voltmeter Scale – use the 2 V max setting and keep the voltage less than 1 V
Part B – Testing Ohms Law
1.) Wire
Ammeter Scale – use the high scale (10A) setting and make sure the plugs are attached to the correct jack.
Voltmeter Scale – use the 2 V max DC scale setting and use voltages 0.25 - 2 V as you vary it
2.) White Bulb
Ammeter Scale – use the mA (milli Amp) setting and make sure the plugs are attached to the correct jack.
Voltmeter Scale – use the 20 V max DC scale setting and use voltages of 1-6 V as you vary it
3.) Clear Bulb
Ammeter Scale – use the mA (milli Amp) setting and make sure the plugs are attached to the correct jack.
Voltmeter Scale – use the 20 V max DC scale setting and use voltages of 1-6 V as you vary it
117
Procedure – READ THE STEPS FIRST, THEN DO IT. Please check off each step
as you read it, the first step has been checked for you.
PART A – Wire Length Investigation
x
___ 1.) Make sure the Ammeter is on the high setting and the plugs are in the proper jacks. Ask
your teacher if you are unsure how it should be setup.
____ 2.) Connect the wire, Power Supply, Ammeter, and thin wire on the board as shown in the diagram. DO
NOT connect the voltmeter until everything else is connected. Be sure the Ammeter and the Voltmeter are
connected as shown. The connection wires in the diagram have been numbered for your reference; the
thin metal wire being investigated is on the board as shown. We will call this the “main wire”
When hooking up your equipment,
Start with the power supply and
put the voltmeter on a after
everythingelse is hooked up.
2
1
Voltmeter
4
5
Thin Wire
on Board
Ammeter
Power Supply
3
____ 3.) Move connecting wires 2,3,4,5 so that length (L) of the main wire between the clips will measure 60 cm
and make sure the clips are tight on the wire. Be sure wires 2,4 and wires 3,5 are clipped directly on
the wire and right next to each other as shown in the diagram
118
____ 4.) Do not turn the power supply on yet. Now we need to choose a voltage to use for this part. This step is
simply to record the voltage that you want to use and is randomly chosen by you. Chose any voltage
between 0.5-1 V and record it here ________ V, then transfer that value into the chart below. Fill that
value down in the table for all lengths since we want to use the same voltage each time in this part
of the lab.
____ 5.) First make sure your Ammeter is setup to the proper scale as described in step 1, turn the power supply
back on and use the voltage selected in step #4. NOTE: you will have to adjust the knob each time
you make a change to be sure the voltage reads your selected value since it can change when
the circuit itself changes. Using the Ammeter, observe the current in the wire and record it in the chart
on the next page, then TURN OFF the power supply.
____ 6.) Change length L of clips 2,4 and 3,5 on the wire to be 70 cm. Make sure 2,4 and 3,5 are directly next to
each other. Turn the power supply back on and adjust it back to the proper voltage, MAKE SURE THE
VOLTAGE IS THE SAME VALUE AS BEFORE as it has probably change due to moving the wires.
Record the new current and then turn off the power supply.
____ 7.) Continue in this manner with lengths L of 80, 90, 100 cm. Find the data collection table a few pages
forward and record all data on the table with proper units
PART B – Testing OHMS Law
I.) WIRE
- You will now apply different potentials (voltages) to the thin wire. Be sure you read the value of the voltage
from the voltmeter attached directly to the wire (not on the power supply itself) and KEEP THE VOLTAGE
BELOW 2 VOLTS.
1.)
AMMETER - Make sure your Ammeter is still set to the high setting as used in Part A of the lab.
VOLTMETER - The Voltmeter should be set to the 2V max setting as in Part A of the lab.
2.) Set the wire to a length of 90 cm
3.) Start with a voltage between 0 - 0.5 V and record the current and potential in the chart below
4.) Continue to change the voltage to obtain a total of 6 measurements at different potentials, again DON’T GO
HIGHER THAN 2 VOLTS. TURN OFF POWER SUPPLY WHEN DONE. Record the data in the data collection
tables with proper units.
II.) WHITE BULB
1.) Disconnect the “thin wire” and replace it with the white light bulb and move both clips onto the bulb exactly
as they were attached to the wire. The clips can be attached to the bulb connection and also be clipped onto one
another on either side of the bulb.
2.) AMMETER - CHANGE THE AMMETER SETTING – Remove the wires plugged to the Ammeter and use the
proper jacks to set the Ammeter scale to the mA scale setting. (Make sure you have a 60W or less wattage
bulb, ask your teacher if your bulb is above 60 W)
3.) VOLTMETER - CHANGE THE VOLTMETER SETTING – Move the voltmeter scale up to the 20 V max scale.
4.) Apply varying potentials and take readings of current at each one. Record your data in the data collection
tables with proper units. Use slightly larger increments than in part I of this section but keep the maximum
potential below 6V. The bulb may or may not light up.
119
III.) CLEAR BULB
1.) Remove the white bulb and replace it with the clear bulb.
2.) AMMETER – leave the Ammeter scale to the mA scale setting used in part II
3.) VOLTMETER – Use the 20 V max scale, same as with the white bulb.
4.) Apply varying potentials and take readings of current at each one. Record your data in the data collection
tables using proper units. Use slightly larger increments than in part I of this section but keep the maximum
potential below 6V. The bulb will not light up.
120
121
Ohms Law Lab
Name: __________________
Data Collection Tables
WIRE
Length (L)
Potential (V)
Current (I)
60 cm
70 cm
80 cm
90 cm
100 cm
WIRE
Potential (V)
Current (I)
White
Bulb
Potential (V)
Current (I)
Clear
Bulb
Potential (V)
Current (I)
Use the extra columns above to calculate the resistances. Show one sample calculation beside the first table
122
Graphs:
For each graph that you will be creating, be sure to label them. Your
title should not only include what quantities are being graphed but also
for what item the graph is for (ex: Potential vs. Current (White Bulb))
Each graph should be on its own page FULL SIZE GRAPH
Best fit lines should be drawn with data points shown. Keep in mind that a best
fit “line” can be a curve if a curve happens to be the type of line that would best
represent the trend shown by the data. DO NOT simply connect the dots.
A special note about graph scales. If you have similar data (numbers like 100, 110, 105, 115),
excel will automatically choose a very small scale which will make the graph look very sporadic even though it
should basically be a straight line showing very little variation. In this case, you have to click on the axis and
change the max and min scale setting to get a more reasonable scale.
Create the following graphs: (MAKE SURE YOU KNOW WHICH IS Y and which is X, we did this all year)
1.) From Part A
- Title it Æ
Graph 1: Wire: Resistance vs. Length
2.) From Part BI
3.) From Part BI
- Title it Æ
- Title it Æ
Graph 2: Wire: Resistance vs. Potential (Voltage)
Graph 3: Wire: Potential vs. Current
4.) From Part BII
5.) From Part BII
- Title it Æ
- Title it Æ
Graph 4: White Bulb: Resistance vs. Potential (Voltage)
Graph 5: White Bulb: Potential vs. Current
6.) From Part BII
7.) From Part BII
- Title it Æ
- Title it Æ
Graph 6: Clear Bulb: Resistance vs. Potential (Voltage)
Graph 7: Clear Bulb: Potential vs. Current
Graph Analysis:
1.) Under graph 1, write one or two sentences to explain if the graph makes sense.
2.) Graphs 2 and 3 represent the wire. Under each graph, simply write OHMIC or NON-OHMIC and then write
one or two sentences to explain how you know.
3.) Repeat step 2 for graphs 4 and 5 (white bulb), and then also 6 and 7 (clear bulb).
123
Questions:
1.) Draw a schematic circuit diagram of this lab setup when the light bulb was attached.
2.) Define Ohms Law and explain what it means for a material to uniformly “obey” the law. What are the
physical conditions that hold for a material that uniformly obeys the law.
124
125
Series Circuit Lab Investigation
Name: ____________________
Teacher notes for Series Lab
- Preferably use combinations of 10, 15 and 20 ohm resistors or even very high resistors with a milliAmp
ammeter setting, but resistors less than 5 ohms are not recommended.
- Have students draw both schematics before doing the lab.
- Explain to students.
How to use multimeter for Voltage, 20 V setting
- Voltmeters go in parallel
How to use multimeter for Current, high setting
- Ammeters go in series, harder to put in since you must disconnect your circuit to add it.
METERS always go on last after everything else is connected.
Always refer to your schematic to see how things should be connected
Part 1 uses bulbs and batteries
- don’t leave connected for long periods of time
Part 2 uses resistors and power supply
- After circuit is connected, we set the voltage of the power supply, so voltmeter must be hooked directly
to the power supply. After that, simply unplug the power supply and do not touch the knob when making
the measurements for this setup. When removing resistors, start again and re-measure the power supply
voltage.
126
SCHEMATICS -
(Draw them neatly, and large… USE A RULER)
A.) Bulbs Schematic
Draw a schematic of a series circuit with three bulbs and a battery with a voltmeter across the battery. Also draw
a voltmeter across each bulb
B.) Resistors Schematic
Draw a schematic of the series circuit with the three resistors and the power supply with a voltmeter across the
battery and use a ruler. Also put three voltmeters across each resistor and put 4 ammeters in the circuit (one
ammeter after each device .. battery, resistor1, resistor2, …)
127
Part 1 – Light Bulb Investigation – DO NOT LEAVE THE BULBS
CONNECTED FOR EXTENDED PERIODS OF TIME, THE BATTERIES
WILL WEAR OUT QUICKLY. TURN ON, TAKE A READING,
DISCONNECT.
You will be using the schematic drawn earlier to help you setup your circuit. In this part of the lab you will be
using two AA batteries connected in a battery holder as your power source and mini light bulbs as loads in the
circuit. Check off each step as you read and do it.
____ 1.) Using only the batteries, bulbs and wires, setup the circuit as drawn but only with a single bulb. DO NOT
CONNECT all three bulbs and don’t put the voltmeter on. The actual circuit you create in real life should look just
like your picture but with only 1 bulb. This is a very simply circuit connection.
____ 2.) When your circuit is complete, the bulb should be lit. Make a mental
observation of the brightness of the bulb. Use the multimeter (set for voltmeter
operation) to measure the voltage drop across the bulb. REMEMBER, THE
VOLTMETER GOES AROUND WHAT YOU ARE MEASURING AS SHOWN IN THE
DIAGRAM. Record your values here and disconnect the battery after taking the
reading.
Voltmeter
BULB
____ 3.) Add a second bulb to the circuit and reconnect the battery. Make an observation of the brightness of
the bulbs and measure the voltage drop for each bulb and record the results; disconnect the battery. State your
observations.
____ 4.) Add a third bulb to the circuit and reconnect the battery. Again make an observation of the brightness
of the bulbs and measure the voltage drop for each bulb and record the results; disconnect the battery. State
your observations.
____ 5.) (a) Disconnect the battery holder and use the voltmeter (multimeter) to directly measure the total
potential of the batteries connected in the battery holder and record it.
____ (b) Compare your results in this part (5) to the total voltages from each measurement above, state your
observations and explain discrepancies if possible.
128
Part 2 – Resistor Investigation
IN THIS PART OF THE LAB WE WILL USE A POWER SUPPLY. DO NOT LEAVE
THE POWER SUPPLY ON FOR EXTENDED PERIODS OF TIME. TURN IT ON,
TAKE YOUR READINGS AND THEN TURN IT OFF OR UNPLUG IT.
___ 1.) (a) Using the same circuit created for the bulbs, simply remove the bulbs and replace each bulb with a
resistor from the bag. Also remove the batteries used and replace them with a power supply, you might have to
change the wires to connect the power supply properly.
____ (b) Each resistor is labeled with a predefined resistance, be sure to label it on the schematic
diagram you drew earlier and make sure your circuit looks like the schematic.
____ 2.) With your full circuit connected, turn on the power supply and set it up to produce 3V of potential and
be sure to use the voltmeter (multimeter) directly on the power supply to make sure the voltage produced is 3V.
____ 3.) With the power supply producing 3V of potential, use the multimeter to measure the potential across
each resistor and record the results on the schematic diagram drawn before. Turn off or unplug power supply
when not taking readings.
____ 4.) In this part of the lab, you will use an ammeter to measure currents. Since there is only 1 ammeter per
group, you will have to unhook some wires and move the ammeter from one
Ammeter
location to the next. REMEMBER THE AMMETER DOES NOT GET
ATTACHED THE SAME WAY THE VOLTMETER DOES. YOU HAVE TO
DISCONNECT WIRES IN THE CIRCUIT AND INSERT THE AMMETER
NEXT TO THE DEVICE YOU ARE MEASURING; IT DOES NOT GO
AROUND IT. SETUP THE AMMETER TO THE PROPER SETTING AS
Resistor
INSTRUCTED BY YOUR TEACHER
Put the ammeter in the first position and use it to measure the current there. Record the result on the diagram.
Move the ammeter around the circuit so that it will be in each position and record to results on the diagram.
Turn off or unplug power supply as you change the circuit.
____ 5.) Remove one of the resistors and redraw and label your schematic below, be sure you have two
different resistance resistors in the circuit. Repeat steps 2-4, be sure to check the voltage of the
power supply with the multimeter as it will most likely change and need to be readjusted back to 3
Volts. Record all measured values on the diagram including total current and voltage from the power supply
itself
129
Series Circuit Lab Analysis
Name: _________________
What to turn in: ATTACH TO THE BACK, THE SCHEMATICS YOU DREW ON THE
SECOND PAGE, then for the rest of the lab only turn in from this page forward.
1.) (a) List the results from the 3 resistor
setup in the table with proper units.
Calculate the resistance of each resistor in
the 3 resistor setup. Find the percent error
for the total calculated resistance vs. the
total actual resistance listed on the resistor
itself.
Resistor
Listed
Resistance
Voltage
Current
Calculated
Resistance
______
______
______
______
R1
R2
R3
Totals
(b) Using your measured values from lab day of the power supply voltage and current, fill in the first two rows of
the table below. Using those values, calculate a total resistance based on the power supply values only.
Note, this should be slightly different than the sum of the individual resistances
Measured
Current
Measured
Voltage
Calculated
Resistance
Power
Supply
Note: Do not sum the resistance from
the table in part (a) to get the total
resistance here, use ohms law with
measured V and I instead.
2.) Repeat the above analysis for the two resistor setup.
Resistor
Listed
Resistance
Voltage
Current
Calculated
Resistance
______
______
______
______
Measured
Current
Measured
Voltage
R1
R2
Totals
(b)
Calculated
Resistance
Power
Supply
130
Questions:
1.) What happens to the brightness of light bulbs when more are added to a series circuit. Explain briefly.
2.) Referring specifically to the results from your tables in step 1 on the prior page, does the experiment
“approximately” verify the rules for series circuits learned in class? Explain briefly, no need to write a long
paragraph but be sure to refer to your specific data. No need to do error analysis here, simply state
results.
- Explain Resistance -
- Explain Current -
- Explain Voltage -
3.) Comparing the results from parts 1 and 2 from the prior page, briefly comment on how removing a resistor
changes the total current and resistance. State your results and give a brief explanation why this happened.
(extra room is provided at the top of the next page if needed)
131
Error Analysis:
There should be some minor discrepancies in your data in this lab.
(a) There should be discrepancies in parts 1(a) and also in part 1(b) of the analysis. Describe these
discrepancies, no need to explain, just list them
(b) There should also be discrepancies comparing parts 1(a) and 1(b) or parts 2(a) and 2(b) of the analysis.
Describe these discrepancies, no need to explain, just list them
(b) Can you account for these discrepancies? Please answer briefly if possible.
132
133
Parallel Circuit Lab Investigation
Name: ____________________
134
SCHEMATICS -
(Draw them neatly, and large… USE A RULER)
A.) Bulbs Schematic
Draw a schematic of a parallel circuit with three bulbs and a battery with a voltmeter across the battery. Also
draw a voltmeter across each bulb. Use a ruler for all.
B.) Resistors Schematic
Draw a schematic of the parallel circuit with the three resistors and the power supply with a voltmeter across the
battery and use a ruler. Also put three voltmeters across each resistor and put 4 ammeters in the circuit (one
ammeter after each device .. battery, resistor1, resistor2, …)
135
Part 1 – Light Bulb Investigation – DO NOT LEAVE THE BULBS
CONNECTED FOR EXTENDED PERIODS OF TIME, THE BATTERIES
WILL WEAR OUT QUICKLY. TURN ON, TAKE A READING,
DISCONNECT.
You will be using the schematic drawn earlier step to help you setup your circuit. In this part of the lab you will
be using two AA batteries connected in a battery holder as your power source and mini light bulbs as loads in the
circuit. Check off each step as you read and do it.
____ 1.) Using only the batteries, bulbs and wires, setup the circuit as drawn in your schematic. DO NOT
CONNECT any ammeters or voltmeters to the circuit. When connecting the circuit, you should start with a single
wire from the power supply and then connect three other wires to the end of this wire in order to make the
junction. Connect each device and make a junction on the other side before returning to the power supply so
your real circuit looks just like your schematic
____ 2.) When your circuit is complete, all three bulbs should be lit. Make a mental
observation of the brightness of the bulbs. Use the multimeter (set for voltmeter
operation) to measure the voltage drop across the bulb, then disconnect the battery.
REMEMBER, THE VOLTMETER GOES AROUND WHAT YOU ARE MEASURING
AS SHOWN IN THE DIAGRAM. Record your values here.
Voltmeter
BULB
____ 3.) Disconnect one side of one of the bulbs. Leave the bulb in place, just disconnect it. Reconnect the
battery and note that the disconnected bulb should be out. Make an observation of the brightness of the bulbs.
Note that a very slight change in brightness should be ignored and considered as no change. There is a
secondary effect for why bulb brightness changes slightly when adding and removing. Measure the voltage drop
for each bulb and record the results (you will also notice minor changes in the voltage). Disconnect the battery;
State your observations
____ 4.) Disconnect one side of another bulb. Again leave the bulbs in place, simply disconnect them.
Reconnect the batteries and again make an observation of the brightness of the bulb (only one bulb should be lit
now). Measure the voltage drop for the bulb and record the results. State your observations.
5.) (a) Disconnect the battery holder and use the voltmeter (multimeter) to directly measure the total potential of
the batteries connected in the battery holder and record it.
(b) Compare your results in this part (5) to the total voltages from each measurement above, state your
observations and briefly explain discrepancies if possible.
136
Part 2 – Resistor Investigation
IN THIS PART OF THE LAB WE WILL USE A POWER SUPPLY. DO NOT LEAVE
THE POWER SUPPLY ON FOR EXTENDED PERIODS OF TIME. TURN IT ON,
TAKE YOUR READINGS AND THEN TURN IT OFF OR UNPLUG IT.
___ 1.) (a) Using the same circuit created for the bulbs, simply remove the bulbs and replace each bulb with a
resistor from the bag. Also remove the batteries used and replace them with a power supply, you might have to
change the wires when you do this.
____ (b) Each resistor is labeled with a predefined resistance, be sure to label it on the schematic
diagram you drew earlier and make sure your circuit looks like the schematic.
____ 2.) With your full circuit connected, turn on the power supply and set it up to produce 3V of potential and
be sure to use the voltmeter (multimeter) directly on the power supply to make sure the voltage produced is 3V.
____ 3.) With the power supply producing 3V of potential, use the multimeter to measure the potential across
each resistor and record the results on the schematic diagram drawn before, then turn off or unplug the power.
____ 4.) In this part of the lab, you will use an ammeter to measure currents. Since there is only 1 ammeter per
group, you will have to unhook some wires and move the ammeter from one
Ammeter
location to the next. REMEMBER THE AMMETER DOES NOT GET
ATTACHED THE SAME WAY THE VOLTMETER DOES. YOU HAVE TO
DISCONNECT THE CIRCUIT AND INSERT THE AMMETER NEXT TO THE
DEVICE YOU ARE MEASURING; IT DOES NOT GO AROUND IT. MAKE
SURE THE AMMETER IS SET TO THE PROPER SCALE AS INSTRUCTED
Resistor
BY YOUR TEACHER
Put the ammeter in the first position and use it to measure the current there. Record the result on the diagram.
Move the ammeter around the circuit so that it will be in each position and record to results on the diagram.
Turn off of unplug the ammeter after taking each reading.
____ 5.) Remove one of the resistors and redraw and label your schematic below, be sure you have two
different resistance resistors in the circuit. Repeat steps 2-4, be sure to check the voltage of the
power supply with the multimeter as it will most likely change and need to be readjusted back to 3
Volts. Record all measured values on the diagram including total current and voltage from the power supply
itself.
137
Parallel Circuit Lab Analysis
Name: _________________
What to turn in: ATTACH TO THE BACK, THE SCHEMATICS YOU DREW ON THE
SECOND PAGE, then for the rest of the lab only turn in from this page forward.
1.) (a) List the results from the 3 resistor
setup in the table with proper units.
Calculate the resistance of each resistor in
the 3 resistor setup. Find the percent error
for the total calculated resistance vs. the
total actual resistance listed on the resistor
itself.
Resistor
Listed
Resistance
Voltage
Current
Calculated
Resistance
______
______
______
______
R1
R2
R3
Totals
Note: RTOT should be REQ for a parallel circuit, not the sum.
(b) Using your measured values from lab day of the power supply voltage and current, fill in the first two rows of
the table below. Using those values, calculate a total resistance based on the power supply values only.
Note, this should be slightly different than the sum of the individual resistances
Measured
Current
Measured
Voltage
Calculated
Resistance
Power
Supply
Note: Do not sum the resistance from
the table in part (a) to get the total
resistance here, use ohms law with
measured V and I instead.
2.) Repeat the above analysis for the two resistor setup.
Resistor
Listed
Resistance
Voltage
Current
Calculated
Resistance
______
______
______
______
Measured
Current
Measured
Voltage
R1
R2
Totals
(b)
Calculated
Resistance
Power
Supply
138
Questions:
1.) What happens to the brightness of light bulbs when more are added to a parallel circuit. Explain briefly.
2.) Referring specifically to the results from your tables in step 1 on the prior page, does the experiment
“approximately” verify the rules for parallel circuits learned in class? Explain briefly, no need to write a long
paragraph but be sure to refer to your specific data. No need to do error analysis here, simply state
results.
- Explain Resistance -
- Explain Current -
- Explain Voltage -
3.) Comparing the results from parts 1 and 2 from the prior page, briefly comment on how removing a resistor
changes the total current and resistance. State your results and give a brief explanation why this happened.
139
Error Analysis:
There should be some minor discrepancies in your data in this lab.
(a) There should be discrepancies in parts 1(a) and also in part 1(b) of the analysis. Describe these
discrepancies, no need to explain, just list them
(b) There should also be discrepancies comparing parts 1(a) and 1(b) or parts 2(a) and 2(b) of the analysis.
Describe these discrepancies, no need to explain, just list them
(b) Can you account for these discrepancies? Please answer briefly if possible.
140
141
Name: ____________________________________________
Magnetic Field Map
Part 1 – Mapping magnetic Flux Lines of a Single bar magnet
1.) Take out a single bar magnet and compass. Make sure there are no other magnets on the desk, only ONE
bar magnet and the compass. Move the compass near the N pole of the magnet and note the part of the
compass magnet that is pointing away from the N pole of the bar magnet would be the N pole of the compass
magnet (since likes repel). NOTE: the north pole of your compass might change during the course of this lab,
each compass is very weak and can easily be remagnetized by the bar magnet nearby.
2.) Take a piece of white paper and turn it landscape style so it is wider than it is high. Place a bar magnet in the
middle of the paper and trace around the magnet. Remove the magnet to label the N and S poles on the paper
and then put the magnet back in place on the paper.
3.) Place the compass on the paper near the N pole of the magnet touching it.
Make a dot on both sides of the compass where the arrow is pointing.
dot
dot
N
Remove the compass and draw an arrow to indicate the direction the N pole of the compass is pointing as shown
in the diagram below (DO NOT DRAW THE CIRCLE THOUGH).
4.) Move the compass so that the back end of the arrow touches the second dot that you made. MAKE SURE
THE BACK OF THE ARROW EXACTLY TOUCHED THE PRIOR DOT. Put another dot on the tip of the arrow in the
new location and draw the next arrow, again don’t draw the circle.
new dot
5.) Continue to move the compass (head to tail) until you return back to the magnet or run off the page, draw
arrows each time.
142
6.) Once you have a complete loop, start the compass at a new location near the magnet and repeat the
process. Continue in this manner until you have sufficient (you will probably need 10 or more) complete loops to
accurately show the flux lines around the magnet.
Part 3 – Mapping magnetic Flux lines of two bar magnets
1.) If you are using small size magnets and compass, you can do this part with a single sheet of paper. If you
have larger bar magnets you will have to tape to pieces of paper together
Repeat the process from part 2 with two bar magnets separated by about 5 cm (about two finger widths). Space
the magnets with opposite poles facing each other. If you have a large magnet only one pole of each magnet
might be on the paper. (see diagram below).
N
S
2.) Repeat the process above for magnets with like poles facing each other.
ARE YOU DONE? DO YOU HAVE THREE DIAGRAMS TOTAL?
143
Name: ____________________________________________
Strength of a Magnet
Introduction
In this experiment, you will measure the strength of a magnetic field as you move away from a magnet. This will
be accomplished by measuring the relative effect of a magnet on the earth’s magnetic field.
When a compass is away from external magnet’s, only the earths magnetic field effects it and the direction points
in direction of geographic north (which is actually the earth’s magnetic south pole, in canada).
Ex:
Compass with no magnets near by
Pointing towards geographic north (earth magnetic S)
-------------------------------------------------------------------When an external magnet is brought near the compass, it can override the earth’s magnetic field and cause the
compass to deflect. The closer the magnet is to the compass, the more the deflection will be. This deflection
can be used to measure the relative strength of the magnet at certain distances compared to the strength of the
earth
Bring a magnet near
S
Magnet is too far away to influence the compass
--------------------------------------------------------------------
S
Magnet very close overpowers the earth’s magnetic field to a large degree, only angles up slightly
144
Prelab Questions
1) In the example presented on the prior page, what would the orientation of the needle be when the strength of
the external magnet’s field and the strength of the earth’s magnetic field had exactly equal effects on the
compass. Draw it below.
2) This compass direction (from above) is the resultant field B. This resultant is the combination of the earth’ s
magnetic field BE and the magnet’s magnetic field BM.
Draw a vector sketch of BE and BM showing how they combing to make the resultant field B
145
Procedure
1.) Take a sheet of paper and turn it sideways. Use a ruler and draw a vertical line with an arrow on top near the
left edge of the paper
2.) If using a large size magnet, take a second sheet of paper and tape it to the first sheet (as shown), then use
a ruler and draw a horizontal line across. If using a small size magnet, don’t tape a second sheet on, but do
draw the horizontal line across the single sheet.
3.) Place your paper in a location indicated by your teacher and make sure that all metal objects and bar magnets
are far away from your paper. Place a compass on your paper on top of the vertical line. Your compass should
only show the direction of the earth’s magnetic field (BE) since no other magnets are near by.
Note that the compass is pointing in a different direction as my vertical line
4.) Starting at your vertical arrow line, measure 4 cm to the right and make a
series of lines at 4 cm increments parallel to your vertical line at each location.
Each one of these lines will represent the direction of the earth’s magnetic field at
each location.
5.) Put your compass on the first vertical line. We want our vertical lines to show the direction of
the earth’s magnetic field, so rotate the paper, or even better rotate the object the paper is
resting on, so that the compass direction lines up with the vertical line drawn on the page
as shown. (You cant just rotate the compass since the compass will not change its
preferred direction controlled by the earth’s magnetic field)
Slide your compass along the horizontal line to make sure that it does not change
its direction and to verify there are no stray magnetic fields from other random
objects nearby, and then tape the paper down so it won’t move.
If the compass deflects as you slide it, you need to find a new location for your paper
6.) Move the compass to the first line to the right of your vertical line and place the N pole
of a bar magnet on the vertical line as shown in the diagram below. Tape the magnet down.
Put the center of the compass directly on the intersection of the vertical and
horizontal line.
s
n
Note that the bar magnet now interferes with the earths magnetic field and causes the compass to turn.
146
BE CAREFUL ON TO DISTURB THE SETUP FROM THIS POINT ON, WE WANT EVERYTHING TO STAY EXACTLY AS
WE HAVE ORIENTED SO THE RESULTS WILL BE CONSISTENT.
7.) Make dots on both ends of the compass where the arrows are pointing. This compass direction is the
direction of the resultant magnetic field from the bar magnet and the earth together. Use a ruler and draw a line
connecting these dots to show the direction of deflection at this location. The center of this line should exactly
line up with the intersection of the vertical and horizontal guide line on the paper.
8.) Keep the bar magnet in the same location and continue to move the compass to each 4cm increment where
the vertical and horizontal lines intersect. As before, use the compass and draw dots and a line to represent the
direction of the resulting magnetic field at that location and draw a single arrow at each spot. NOTE THAT YOU
ARE NOT CONNECTING LINES TOGETHER AS YOU DID IN THE MAGNETIC FIELD MAP LAB, here you are simply
placing the magnet on each vertical line directly at the intersection of the horizontal line and showing the way the
field points at this location.
Continue to move the compass to each position until the direction of the compass line is parallel to the vertical
lines or until you run out of paper.
Analysis Instructions
Your finished product will be a series of intersecting lines that gradually change as you move left to right.
Remember that the pre-drawn vertical lines represent the earth’s magnetic field, while the lines drawn where the
compass was pointing represents the resultant field of the earth and the magnet.
The angle θ measured from the vertical line is a measure of how strong the bar magnet is overcoming the earths
magnetic field. Logically, the larger the angle, the more effect the magnet is having on the normal orientation of
the compass. The angle can easily be found by measuring it with a protractor, do this at each spot.
A measured angle of 90 or 0 degrees should be excluded from the chart and the point ignored.
θ
BE SURE TO MEASURE THE ANGLE AS SHOWN IN THIS DIAGRAM, FROM THE
VERTICAL LINE, NOT THE HORIZONTAL LINE.
147
Magnet Strength Lab
Name: __________________
1.) Complete the table below: the distances are known values (refer to lab procedure), the angles were measured
above, tan θ can be found simply by using your calculator tan button, and 1 / d2 is similarly easily found with
your calculator
Data Table
Distance away from
magnet (d)
cm
Deflection angle (θ)
(° )
Tan θ
1 / d2
(cm-2)
3.) In the data table, we found a value of tan θ. Tan θ is a ratio of opp/adj side of a triangle, and in this lab that
represents the ratio of the magnets field strength to the earths magnetic strength (since those were the opp and
adjacent sides of the resultant field, refer to prelab if you are confused). A value of 1.0 would indicate that the
earth field and magnet field are equal, a value of 10 would mean the magnet is 10 times stronger than the earth
Make a graph of tan θ vs. distance to show how the magnet effect varies as you move away from it. Attach this
graph to the back of the lab.
What does the shape of this graph indicate about the specific way that the magnet strength varies as the
distance from the magnet increases?
148
4.) The last column of the table above is 1 / d2 or d-2 which is an inverse squared. Tan θ is a measure of the
strength of the magnet. Graph tan θ vs. 1/d2 to check and see if there is a direct relationship between these two
quantities. If this direct relationship proves true, we will then see that the field strength does in fact vary
inversely with the distance away from a magnet. Comment on your results.
5.) Based on what you know about the vector quantities involved in this lab and how they interact, show a vector
diagram representing the resultant field made up of equal field strengths from the earth BE and the magnet BM.
(Refer to prelab) Based on this diagram, what is the angle θ at which this would occur?
6.) Using your answer to #5 and your data table, or graph, determine at what distance “d” the two fields BE and
BM would have equal magnitudes. (You will have to read the distance from the graph to correlates to the angle
you chose in question #5)
149
Name:
Pendulum
A pendulum swings back and forth. The motion repeats with each
swing. The concepts of cycle, period, and amplitude are used to
describe repetitive motion.
•
•
•
A cycle is one complete back and forth motion.
The period is the time it takes to complete one full cycle.
The amplitude is the amount the pendulum moves away
from its resting position.
In this experiment we will explore what
affects the motion of the Pendulum.
Setting Up
Use the string and weights to make a pendulum.
•
•
•
The clamp allows you to easily change the length of the string.
Extra weight can be added to the pendulum as you choose.
The angle of release (amplitude) can be measure and changed with a protractor
When timing pendulum swings to find the Period of motion (time for 1 swing), be sure to
use at least 10 swings back and forth to get a more accurate result
Which of the three things (length, weight, and angle) do you think has the biggest effect
on the Pendulum?
________________________________________________________________________
________________________________________________________________________
________________________________________________________________________
150
A: The Effect of Weight:
The first experiment looks at whether changing the weight affects the period of the Pendulum. Keep the
string length and the amplitude constant.
String length
_____________________
Weight of Bob
Amplitude
_______________________
Time For Ten Cycles
(seconds)
Period
(seconds)
Graph your data: Make sure that the scale on your x and y axis is appropriate (do not make your scale
over a very short range, rather use a normal number scale). If done with excel, you will have to adjust the axis
max and min scale setting. Be sure to title it and label everything.
151
B: The Effect of Amplitude:
The second experiment looks at whether changing the amplitude of the swing
changes the period. Keep the string length and weight constant.
String length
_____________________
Amplitude
(degrees)
Weight of Bob
________________
Time For Ten Cycles
(seconds)
Period
(seconds)
Graph
152
C: The Effect of String Length:
The third experiment looks whether changing the length of the string changes the period.
Keep the weight and amplitude constant.
Amplitude
_____________________
String Length
(cm)
Weight
________________
Time For Ten Cycles
(seconds)
Period
(seconds)
Graph
153
Questions
1.) Which factor has the largest effect on pendulum period?
2.) Explain the actual physics reasons why each factor had or did not have an effect on the period. Do not simply
state that the factor is not in the formula, rather give actual physical reasons for each effect based on forces,
masses and the motions themselves.
------------ Continued --------------
154
3.) The equation for the period of a pendulum on a string is
T = 2π
l
g
Chose 1 set of results and calculate an experimental value of g based on the length of the string in that setup.
Compare (% error) the calculated value of “g” to the actual known value. Be sure to explicitly state which
measured values you are using and show all work and substitution when solving for the unknown.
155
WAVE PULSES ON A COIL SPRING
Coiled springs are excellent materials for
analyzing a variety of wave behaviors. In
this activity, you will examine transverse and
longitudinal pulses, fixed- and free-end
reflections, constructive and destructive
interference, standing waves, and the
behavior of waves when they reach new
transmitting media.
TRANSVERSE PULSES
A. Send a transverse pulse down a stretched large coil spring. Observe the motion of the
spring’s coils. Draw a sketch of the pulse traveling down the spring.
Why is this pulse called a transverse pulse?
B. Observe the speed of the pulse while varying the pulse amplitude. What happens to the
speed of the pulse as the amplitude changes?
C. Observe the speed of the pulse while varying the tension in the spring. What do you notice
about the pulse speed with respect to changes in tension?
D. Does the stretched spring under different tensions represent the same or different
transmitting media?
E. Maintain a constant tension and send continuous wave trains of varying frequencies down
the spring. What happens to the wavelength as the frequency increases?
156
WAVE INTERFERNCE
F. Send two pulses of approximately the same amplitude from opposite ends of the spring
toward each other on the same side of the spring. What do you observe?
Do the two disturbances “bounce off” each other or pass right through each other?
What do you notice when the pulses “overlap”?
Draw sketches showing the pulses, labeled “A” and “B”, before, during, and after they
meet.
G. Send two pulses of approximately the same amplitude from opposite ends of the spring
toward each other on opposite sides of the spring. What do you observe?
Do the two disturbances “bounce off” each other or pass right through each other?
What do you notice when the pulses “overlap”?
Draw sketches showing the pulses (labeled “A” and “B”) before, during, and after they
meet.
157
WAVE REFLECTION
H. Hold the spring firmly down in place at the far end and send a pulse down the spring.
Describe and illustrate your observations of reflection from this “fixed end.”
I. Attach and hold a light string on one end of the spring and send a pulse from the other
end. Describe and illustrate your observations of reflection from this “free end.”
WAVE BEHAVIOR AT MEDIA BOUNDARIES
J. Attach the two springs together and send a pulse from the large spring. Record your
observations.
K. What happens to the wave speed when the pulse goes from the large spring to the small
spring?
.…from the small spring into the large spring?
L. Did you notice any reflection when the pulse reached the junction where the two springs
were connected?
Did more of the wave seem to be transmitted or reflected?
Think of a common example where light waves partially reflect and partially transmit when
they reach the boundary of the transmitting media.
158
STANDING WAVES
M. While holding one end of the large spring firmly in place, move the other end of the spring
continuously back and forth to send a continuous wave train down the spring. Adjust your
frequency until a standing wave with two “loops” is obtained.
Now change your frequency of vibration until more loops are formed. Since the speed of
the wave remains constant (do you know why?), shaking the spring with a higher frequency
does what to the wavelength?
In order to obtain standing waves with more loops when the speed of the wave is constant,
what must be done to the frequency of vibration?
How could you determine the wavelength of the wave when a standing wave pattern is
observed?
Draw sketches of standing waves having one, two, three, and four loops. Indicate on your
sketches how the wavelength could be measured.
LONGITUDINAL PULSES
N. Stretch the large spring and send a longitudinal pulse down the spring. Observe the
motion of the spring coils. Draw a sketch of the pulse traveling down the spring.
Why is this pulse called a longitudinal pulse?
159
Speed of Sound and Resonance
Purpose:
The purpose of this lab is to demonstrate resonance of sound waves and determine the speed of sound traveling
in air.
Equipment
Resonance tube (graduated cylinder and inner glass tube), water, tuning forks, meter stick,
Procedure:
Velocity of sound in air
1) Fill the 1 liter graduated cylinder to within two inches from the top with water. Place the inner tube inside the
graduated cylinder.
2) Choose a tuning fork and record its frequency.
f =_________________ Hz
3) Strike the tuning fork with hard rubber and hold the tuning fork horizontally, with its tines one above the other
about 1 cm above the open end of the inner tube. Move both the inner tube and the fork up and down together
to find the air column length that gives the loudest sound. Measure the distance from the top of the resonance
tube to the water level.
Length of the resonance tube = _______________ m
4) Record the diameter of the resonance tube.
Diameter of the resonance tube = ______________ m
5) The air which vibrates and makes sound actually extends slightly beyond the length of the tube itself and we
therefore need to make a correction to find the actual length of air vibrating. This correction is made by adding
0.4 times the diameter of the tube to the measured length of the air column.
Corrected Length = _______________m
6) The vibrating air creates a fundamental standing wave in an open/closed pipe. As such, only ¼ of the
wavelength of this wave fits in the air column length you made. Using this fact, determine the wavelength of
the sound (be sure to use the corrected length when doing this). READ THIS STEP CAREFULLY, READ IT
AGAIN TO BE SURE YOU UNDERSTAND WHAT IT IS SAYING.
Wavelength = _______________m
7) Determine the velocity of sound and record.
Speed of sound in air = ____________m/s
160
8) Repeat each of the above steps for a second tuning fork:
f = ______________ Hz
Length of the resonance tube = ______________ m
Corrected Length = ______________ m
Wavelength = ______________ m
Speed of sound in air = ______________ m/s.
The accepted value for the speed of sound in air is 332m/s at 0C.
The speed of sound in air increases by 0.6m/s for each degree C above zero.
Using the temperature of the room today, compute the accepted value for the speed of sound at room
temperature.
Calculate the percentage difference between this and the average of your two measured values.
161
Refraction and Total Internal Reflection
Using a Laser
NAME: ___________________________________
162
Materials
Handheld Laser
Ruler
Protractor
Semi-Circular dish
Refraction Procedure Part 1
1.) Take out the laser and put the batteries in. Keep the laser dry.
2.) Take a sheet of paper and place the semi-circle dish upside down in the center of the paper (open side
down). Trace the shape of the dish on the paper and remove the dish from the paper.
3.) Repeat step 2 again so you will have two sheets with tracing on them, let each lab partner trace the shape
twice as well.
4.) Fill the dish about halfway with water.
5.) Add two drops of milk to the dish and stir them into the water. The small amount of milk will make the laser
visible in the water, like fog makes lasers visible in air. Shine the laser through the side of the container to verify
that you can see it in the water, if not add a little more milk, but not too much.
6.) Place the semi-circle dish back on the traced paper shape and shine the laser directly perpendicular to the flat
face as shown in the diagram below. Keep the laser and the paper dry.
dish
paper
WHEN USING THE LASER, IT WORKS
BETTER IF YOU RAISE IT VERY
SLIGHTLY OFF THE PAPER SURFACE
SO THE LIGHT RAY DOES NOT HIT
THE BOTTOM OF THE DISH ON THE
PAPER.
laser
QUESTION:
Do you see refraction when the laser enters the dish in the configuration, explain?
163
7.) Using the same setup as before, change the laser orientation so that it is angled to the flat side of the dish
and hits the midpoint of the dish (see diagram). Again hold the laser slightly above the paper surface.
dish
paper
laser
QUESTION:
Do you notice refraction when the laser enters the water, explain?
8.) We are going to make 3 dots to show the path of the laser beam. Using a pencil:
1 - Place a dot (1) at the tip of the laser where the light beam originates,
2 – Place a dot (2) where the beam first hits the flat side of the dish.
(MAKE SURE THE DOT IS PLACED EXACTLY ON THE TRACED LINE, AND NOT ABOVE OR BELOW)
3 – Place a dot (3) where the beam exits the water dish
dot 3
dot 2
dot 1
9.) Remove the laser and dish and USE A RULER to connect the dots with arrowheads to show the path of the
light.
10.) Repeat so each lab partner has their own paper.
164
Total Internal Reflection - Procedure Part 2
1.) Using the same setup as before, place the dish on the second traced sheet.
2.) Turn the paper around 180 degrees so that the circular side is facing you.
dish
paper
laser
In this part of the lab, the laser should always be exactly perpendicular to the curved surface.
3.) Move the laser right next to the curved surface of the dish, holding it slightly off the paper, and hold it so that
the laser light is perpendicular to the surface of the dish. Notice the light ray moving through the water and also
notice a second ray exiting the water into air at the flat side. If you cannot see the exiting ray, put something a
few centimeters behind and to the side of the flat side of the dish so you can see a dot showing where the exiting
laser goes.
4.) Slide the laser from its current position along the curved face always keeping it perpendicular to and touching
the dish, and pay attention to the ray exiting at the flat side of the dish, see diagram. The laser should be
hitting the flat side at the midpoint. Continue to move the laser until the exiting ray no longer exits the
water, but all reflects back inside, this is the critical point for total internal reflection. Slide the laser beam back
and forth to verify you have found the exact position of total internal reflection
5.) We will again make dots to mark the position of the light ray. Make one dot at the tip of the laser where the
ray enters the water, make a second dot where the laser hits the flat part of the dish, and make a third dot
where the reflected ray comes back to the curved surface
dot 2
dot 3
dot 1
6.) Remove the laser and dish, and USE A RULER, to draw the rays. Repeat for other lab partners.
165
ANALYSIS
Part 1 - Refraction
1.) Using your sketch from part 1, USE A RULER and draw a normal line at the flat surface and label the incident
and refraction angle on the diagram, make the normal line long so you will be able to measure the angles
properly. Accurately, measure incident and refraction angles with a protractor and use the table below to record
them. Also label them on the diagram itself.
θi
θr
2.) Using the angles above and the situation shown in the diagram, calculate a value for the index of refraction
of water. Show all formulas and work.
3.) Compare your value of nwater with the best known value nwater = 1.33. What is the % difference? Show formula
and work.
166
Part 2 – Total Internal Reflection
1.) Using your sketch from part 2, USE A RULER and draw a normal line at the flat surface and label the incident
and REFLECTION angle on the diagram, make the normal line long so you will be able to measure the angles
properly. Accurately, measure incident and reflection angles with a protractor and record them in the chart
below, also record them on the diagram itself.
θi
θ’
NOTE: θ’ IS NOT THE REFRACTION ANGLE.
2.) Based on the values from the chart, is the “Law of Reflection” verified, explain?
3.) The incident angle measured in this part is the critical angle (θi = θc) since it was just at the point where total
internal reflection occurred. We are looking at the point where the laser was in the water and was trying to get
into the air, so this is the medium boundary you should be looking at (water to air). Recall the way the refracted
laser aimed just prior to finding the critical point and measuring the angles, this is the point that we want to
analyze where the beam was practically skimming the flat surface. Using the measured incident (critical) angle,
and the techniques for solving total internal reflection problems, solve for the index of refraction of
water. (Note you will not be using θ’ to solve this. By understanding total internal reflection problems, you
should know how to setup the mathematical relationship)
4.) Compare your value of nwater with the best known value nwater = 1.33. What is the % difference? Show formula
and work.
167

Great Neck South Physics Lab Manual

Transcription

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