Lecture-Inelastic Collisions.notebook

Transcription

LectureInelastic Collisions.notebook
November 25, 2012
Happy Ball/Sad Ball Demo:
Click me!
(Do demo while students copy down definitions on next page)
November 25, 2012
Up until now, we have been pushing objects apart. If
we bring objects together, we call that a collision. We
have two types of collisions:
November 25, 2012
Elastic Collision: When objects collide without permanently deforming and without generating heat.
The Result: THEY BOUNCE!!!
November 25, 2012
Elastic Collision: When objects collide without permanently deforming and without generating heat.
The Result: THEY BOUNCE!!!
Inelastic Collision: When objects collide, they distort (get tangled together), and generate heat.
The Result: THEY STICK TOGETHER!!!
In both types of collisions...
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November 25, 2012
MOMENTUM IS CONSERVED!!!
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November 25, 2012
IT IS
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THE
LAW!!!
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The hoverpuck leaves the rubber band launcher with a velocity of 1 m /s. Shortly after it collides and sticks to a second hoverpuck. If each hoverpuck has a mass of 0.3 kg (and they do!!!), how fast do they travel together?
p1,2
p1
November 25, 2012
p1 = p1,2
(Momentum before = Momentum after)
p1,2
p1
November 25, 2012
p1 = p1,2
Since p1,2 has double the mass of p1, what can we say about its velocity?
p1,2
p1
November 25, 2012
p1 = p1,2
Since p1,2 has double the mass of p1, what can we say about its velocity?
p1,2
The velocity of p1,2 is half of p1, so: v1,2 = 0.5 m /s.
p1
November 25, 2012
p1 = p1,2
Here is how we solve with equations and numbers:
p1,2
p1
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p1 = p1,2
p1 = mv1
p1,2
p1
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p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
November 25, 2012
p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
mv1 = 2mv1,2
November 25, 2012
p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
mv1 = 2mv1,2
November 25, 2012
p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
mv1 = 2mv1,2
v1 = 2v1,2
November 25, 2012
p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
mv1 = 2mv1,2
v1 = 2v1,2
v1 = v1,2
2
November 25, 2012
p1 = p1,2
p1 = mv1
p1,2
p1,2 = (m + m)v1,2 = 2mv1,2
p1
mv1 = 2mv1,2
v1 = 2v1,2
v1 = v1,2
2
1 m /s
= 0.5 m /s
2
November 25, 2012
Inelastic Collisions:
2 objects collide and stick together:
p1 + p 2 = p 1+2
Before
Collision
After
Collision
m1 v1 + m 2 v2 = (m 1 + m 2 )v
Remember: Velocity is a Vector!!!
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Senteo TIME!!!
Title Page
November 25, 2012
Radioactive Man (200 kg) flying towards the cannon at 25 m /s catches the 10 kg cannonball (traveling 400 m /s). What is the resulting speed and direction?
B C D A
1
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
+
November 25, 2012
+
Hint: Momentum before = Momentum After
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
November 25, 2012
BEFORE:
pbefore = p1 + p2
p1 = m1 v1
p2 = m2 v2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
+
November 25, 2012
BEFORE:
pbefore = p1 + p2
p1 = m1 v1
p1 = (10kg)(400 m /s)
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
p2 = m2 v2
+
November 25, 2012
BEFORE:
pbefore = p1 + p2
p1 = m1 v1
p1 = (10kg)(400 m /s)
p1 = 4,000 a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
kg*m
/s
p2 = m2 v2
+
November 25, 2012
BEFORE:
+
pbefore = p1 + p2
p1 = m1 v1
p1 = (10kg)(400 m /s)
p1 = 4,000 a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
kg*m
/s
p2 = m2 v2
p2 = (200kg)(25 m /s)
He moves left (negative direction).
November 25, 2012
BEFORE:
+
pbefore = p1 + p2
p1 = m1 v1
p1 = (10kg)(400 m /s)
p1 = 4,000 a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
kg*m
/s
p2 = m2 v2
p2 = (200kg)(25 m /s)
p2 = 5,000 kg*m /s
November 25, 2012
BEFORE:
+
pbefore = p1 + p2 = 4,000 kg*m /s 5,000 kg*m /s = 1,000 kg*m /s
p1 = m1 v1
p1 = (10kg)(400 m /s)
p1 = 4,000 a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
kg*m
/s
p2 = m2 v2
p2 = (200kg)(25 m /s)
p2 = 5,000 kg*m /s
November 25, 2012
AFTER:
pbefore = 1,000 kg*m /s
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pbefore = pafter +
November 25, 2012
AFTER:
pbefore = pafter pafter a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
+
November 25, 2012
AFTER:
pbefore = pafter pafter pafter = (m1 + m2 )v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
+
November 25, 2012
AFTER:
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
+
November 25, 2012
AFTER:
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pafter = (210 kg)v1,2
+
November 25, 2012
AFTER:
+
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pafter = (210 kg)v1,2 = 1,000 kg*m /s
November 25, 2012
AFTER:
+
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pafter = (210 kg)v1,2 = 1,000 kg*m /s
(210 kg)
(210 kg)
November 25, 2012
AFTER:
+
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pafter = (210 kg)v1,2 = 1,000 kg*m /s
(210 kg)
(210 kg)
November 25, 2012
AFTER:
+
pafter = (10 kg + 200 kg)v1,2
a) 4.76 m /s right
b) 4.76 m /s left
c) 42.86 m /s right
d) 42.86 m /s left
pafter = (210 kg)v1,2 = 1,000 kg*m /s
(210 kg)
(210 kg)
v1,2 = 4.76 m /s so 4.76 m /s left
November 25, 2012
Duff Man says:
"That's Enough!!!"

Lecture-Inelastic Collisions.notebook

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