Mass and Weight Worksheet

Name _______________________________________ Date ______________ Period ____________
Mass and Weight Worksheet
Concept questions:
1) Explain the difference between an object’s mass, its weight and the gravitational force on the object.
2) Under what conditions would a scale record a weight for an object which is equal to the magnitude of
the gravitational force on the object?
3) Under what conditions would a scale record a weight for an object which is not equal to the magnitude
of the gravitational force on the object?
4) Describe a situation in which the gravitational force is equal in magnitude to the normal force acting
on an object.
5) Describe a situation in which the gravitational force is NOT equal to the normal force acting on an
object.
6) If an object’s velocity vector and its acceleration vector point in the same direction, what is happening
to the motion of the object?
Which way does the net force vector point?
7) If an object’s velocity vector and its acceleration vector point in opposite directions, what is happening
to the motion of the object?
Which way does the net force vector point?
8) For an object that is at or near the surface of the earth, if you know the weight in Newtons, how do
you calculate the mass in kilograms?
9) For an object that is at or near the surface of the earth, if you know the mass in kilograms, how do you
calculate the weight in Newtons?
Now Calculate- Have fun!!
1) On the moon, the acceleration due to gravity is 1.6 m/s2.
a) If an object has a mass on Earth of 5.1 kg, what is its mass on the moon?
b) If an object has a mass on Earth of 6.7 kg, what is its weight on the moon?
c) If an object has a weight of 100 N on the moon, what is its mass on the moon? On Earth?
2) A 62 kg person stands on a scale in an elevator. The scale reads 607.6 N. Is the elevator
at rest, moving up or down at a constant velocity, accelerating upward or accelerating downward?
CIRCLE all possible answers and show calculations to justify your answer(s).
3) A 105 kg person stands on a scale in an elevator. The scale reads 1500 N.
a) Is the elevator at rest, moving up or down at a constant velocity, accelerating upward or
accelerating downward? CIRCLE all possible answers and show calculations to justify your
answer(s).
b) Calculate the magnitude of the elevator’s acceleration.
4) A 77 kg person stands on a scale in an elevator. The elevator and person are accelerating downward at
-1.3 m/s2.
a) Draw a free-body diagram.
b) What does the scale read?
5) You lift a heavy bag of groceries. The maximum force the bag can withstand without ripping is 160 N.
If you have 13.5 kg of groceries in the bag, what is the maximum acceleration with which you can lift
the bag without ripping it? (Also, draw a free-body diagram.)
6) A search and rescue team is trying to lift an injured hiker out of narrow ravine by means of a cable
dropped from a helicopter. The cable is old and the maximum tension it can withstand without
breaking is 1500 N. The team would like to get the hiker out as quickly as possible and the helicopter
lifts the hiker on a litter with an acceleration of 3 m/s2, upward. If the mass of the hiker and the litter
is 125 kg, does the hiker survive the rescue? (Show your work to justify your answer.) Include a freebody diagram.
If the team was a little smarter about this, at what maximum acceleration could they lift the hiker
without breaking the cable?
7) You are standing on a roof, lowering a can of paint by means of a rope. If the weight of the can and
paint is 52.3 N, and the tension in the rope is 42.5 N, what is the magnitude and direction of the
acceleration of the can of paint? (Include a free-body diagram.)
8) You have dropped a life-size zombie mannequin (attached to a rope) on one of your enemies as he
passes below a window, where you are manically laughing. You need to get it back up quickly before
he tears it apart. In order to accelerate it upward at 3 m/s2, how much pulling force (tension) will you
need on the rope if the zombie has a weight of 21 N? (Include a free-body diagram.)
9) An evil older brother pulls the hair of his younger sister upwards as she sits on the floor. She doesn’t
move upwards, but it sure hurts. If the mass of the younger sister is 45 kg and the normal force the
floor exerts on her is 380 N, what is the magnitude of the pulling force on her hair? (Include a freebody diagram.)
10) A mean older sister pins her younger brother against the floor and tells him she will not let him up
until he steals some cookies for her. If her pinning force is 100 N downward and the boy’s weight is
325 N,
a) Draw a free-body diagram.
b) What is the magnitude and direction of the normal force exerted by the floor on the boy?
c) What is the mass of the boy?
Extra Credit: An object has a weight on Earth of 55 N. If it is taken to Mars, where the acceleration due to
gravity is about 4 m/s2, what is its weight there?