Name: ___________________________
Momentum-Impulse Review
Date: ________
Period: ______
Momentum and Impulse Review
1. Calculate the momentum for the following objects:
a. A tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s
b. A hare with a mas of 2.7 kg moving at a velocity of 7.5 m/s
c. A turtle with a mass of 91 kg moving at a velocity of 1.4 m/s
d. A roadrunner with a mas of 1.8 kg moving at a velocity of 6.7 m/s
2. A person sits in a chair with wheels. When the person stands up, the chair rolls backwards
across the floor. Describe the momentum of the chair in the beginning and at the end.
The initial momentum was zero and the momentum increased after the person stood up.
Explosion collision.
3. A 0.2 kg baseball is pitched with a velocity of 40 m/s and is then batted back to the pitcher with
a velocity of 60 m/s. What is the magnitude of change in the ball’s momentum?
vi = 40 m/s
vf = -60 m/s
Use last equation on equation sheet:
J = change in momentum = -20 kgm/s
m = 0.2 kg
4. What is the law of conservation of momentum?
The initial momentum of an isolated system will be the same as the final momentum of an isolated
system.
5. Identify whether the following collisions are elastic or inelastic:
a. Two balls of dough colliding and then sticking together - inelastic
b. A firework exploding -explosion
c. Two people running into each other and then falling apart -elastic
d. A tennis ball hitting a racket - elastic
6. Which has more momentum, a supertanker tied securely at the dock or a falling raindrop?
Why?
The falling rain drop because it has a velocity.
7. Is the momentum of a car traveling south different from that of an identical car moving north at
the same speed? Explain.
MOMENTUM is different, because momentum has a direction. They are not the same momentum.
8. When you jump off something like a table you let your legs bend at the knees when you strike
the floor. Explain why you would do this.
Increase the amount of time for the collision
9. Why are today’s vehicles designed with crumple zones?
Increase the amount of time for the collision
10. A moderate force will break an egg. Using the concepts of momentum, force, and time interval,
explain why an egg is more likely to break when it is dropped on concrete than if it is dropped
on grass.
More likely to break on concrete because there is a lot of force in a little time.
11. A boxer being hit by a punch tries to move with the punch for best results, whereas a karate
expert delivers a blow to bricks in a short time for best results. Is this a contradiction? Explain.
No, both demonstrate the idea of impulse
12. A baseball pitcher’s first pitch is a fastball, moving at high speed. The pitcher’s second pitch—
with the same ball—is a changeup, moving more slowly. Which pitch is harder for the catcher to
stop? Explain your answer in terms of momentum.
Fastball, more momentum because of higher velocity
PROBLEM SOLVING
14. What velocity must a 1340 kg car have in order to have the same momentum as a 2680 kg truck
traveling at a velocity of 15 m/s to the west?
V = 30 m/s
15. A 0.060 kg tennis ball moves at a velocity of 12 m/s. The ball is struck by a racket, causing it to
rebound in the opposite direction at a speed of 18 m/s. What is the impulse of the racket on the ball?
J = -1.8 m/s
16. A train with a mass of 1,800 kg is moving at 15 m/s when the engineer applies the brakes. If the
braking force is constant at 35,000 N, how long does it take the train to stop?
t = 0.77 seconds
17.An astronaut with a mass of 85 kg is outside a space capsule when the tether line breaks and he is
stranded at rest out in space. To return to the capsule, the astronaut throws a 2.0 kg wrench away
from the capsule at a speed of 14 m/s. At what speed does the astronaut move toward the capsule?
vf = - 0.329 m/s
18.A 0.10 kg toy car initially travelling at 0.195 m/s makes a head-on collision with a 0.15 kg stationary
truck. The final velocity of the 0.10 kg toy car after the collision is 0.045 m/s. Calculate the final
velocity of the 0.15 kg toy truck after the collision.
V = 0.16 m/s
20.A 90 kg halfback runs 8 m/s in the positive direction and is tackled by a 120 kg opponent running in
the negative direction at 4 m/s. Just after the tackle, both players move in the positive direction.
Calculate the final velocity of both players together.
V = 1.143 m/s
21. A train (m=2200 kg) moving at 5.8 m/s crashes into a stationary car (m=1200 kg). The car and train
stay together after the crash. It takes 5.7 seconds for the train and car to come to a complete stop.
a. What is the velocity of the train and car after the collision?
b. What is the acceleration of the train and car after the collision?
a. v = 3.75 m/s
b. a = -0.658 m/s2