Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1) A rubber ball and a lump of clay have equal mass. They are thrown with equal speed
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against a wall. The ball bounces back with nearly the same speed with which it hit.
The clay sticks to the wall. Which one of these objects has the greater momentum
change?
A) the clay
B) the ball
C) Both of them have the same non-zero momentum change.
D) Both of them have zero momentum change.
2) Which of the following quantities are units of momentum? (There could be more than
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one correct choice.)
A) kg s/m
B) N s
C) N m
D) kg m/s
E) kg m2/s2
3) A tiger is running in a straight line. If we double both the mass and speed of the tiger,
the magnitude of its momentum will increase by what factor?
A) 2
B) 16
C) 2
D) 8
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E) 4
4) A very elastic rubber ball is dropped from a certain height and hits the floor with a
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downward speed v. Since it is so elastic, the ball bounces back with the same speed v
going upward. Which of the following statements about the bounce are correct? (There
could be more than one correct choice.)
A) The ball's momentum was conserved during the bounce.
B) The ball had the same momentum just before and just after the bounce.
C) The magnitude of the ball's momentum was the same just before and just after the
bounce.
D) None of the above statements are correct.
5) Two friends are standing on opposite ends of a canoe that is initially at rest with respect
to a frictionless lake. The person in the front throws a very massive ball toward the
back, and the person in the back catches it. After the ball is caught, the canoe is
A) stationary.
B) moving forward.
C) moving backward.
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6) You are standing on a skateboard, initially at rest. A friend throws a very heavy ball
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towards you. You have two choices about what to do with the ball: either catch the ball
or deflect it back toward your friend with the same speed as it was originally thrown.
Which choice should you make in order to maximize your speed on the skateboard?
A) Deflect the ball back.
B) Catch the ball.
C) Your final speed on the skateboard will be the same regardless whether you catch
the ball or deflect the ball.
7) A small car meshes with a large truck in a head-on collision. Which of the following
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statements concerning the magnitude of the momentum change during the collision is
correct? (There could be more than one correct choice.)
A) The magnitude of the momentum change of each one is directly proportional to its
mass.
B) The small car and the truck have the same magnitude momentum change.
C) The magnitude of the momentum change of each one is inversely proportional to
its mass.
D) The truck has the greater magnitude momentum change.
E) The small car has the greater magnitude momentum change.
8) A small car meshes with a large truck in a head-on collision. Which of the following
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statements concerning the momentum during the collision are correct? (There could be
more than one correct choice.)
A) The momentum of the car is constant.
B) The momentum of the truck is constant.
C) The momentum of the car and the momentum of the truck are each constant.
D) The momentum of the car-truck system is constant, but the momentum of each one
separately is not constant.
E) The car and the truck must undergo the same change in speed.
9) Consider two less-than-desirable options. In the first you are driving 30 mph and crash
head-on into an identical car also going 30 mph. In the second option you are driving
30 mph and crash head-on into a stationary brick wall. In neither case does your car
bounce back from the thing it hits, and the collision time is the same in both cases.
Which of these two situations would result in the greater impact force exerted on your
car?
A) hitting the brick wall
B) hitting the other car
C) The force would be the same in both cases.
D) None of the above choices are correct.
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10) A rocket explodes into two fragments, one 25 times heavier than the other. The
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magnitude of the momentum change of the lighter fragment is
A) 5 times as great as the momentum change of the heavier fragment.
B) the same as the momentum change of the heavier fragment.
C) 1/25 as great as the momentum change of the heavier fragment.
D) 1/4 as great as the momentum change of the heavier fragment.
E) 25 times as great as the momentum change of the heavier fragment.
11) Which of the following quantities are units of impulse? (There could be more than one
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correct choice.)
A) kg m2/s2
B) N s
C) N m
D) kg m/s
E) kg s/m
12) Three cars, car X, car Y, and car Z, begin accelerating from rest at the same time. Car X
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is more massive than car Y, which is more massive than car Z. The net accelerating
force exerted on each car is identical. After 10 seconds, which car has the most amount
of momentum?
A) Car Y
B) Car X
C) Car Z
D) They all have the same amount of momentum.
13) During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30
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miles away. This gun also had a very long barrel. What was the reason for using a long
barrel in these guns?
A) to allow the expanding gases from the gunpowder to exert a force on the bullets
for a longer time
B) to exert a larger force on the shells
C) to reduce frictional losses
D) to increase the force exerted on the bullet by the expanding gases from the
gunpowder
E) to reduce the force exerted on the bullet by the expanding gases from the
gunpowder
14) In a collision between two objects of unequal mass, which object receives a greater
magnitude impulse?
A) the object of larger mass
B) the object of smaller mass
C) They receive equal magnitude impulses.
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15) Identical forces are exerted for the same length of time on two different objects. The
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magnitude of the change in momentum of the lighter object is
A) larger than the magnitude of the change in momentum of the larger mass object.
B) zero.
C) exactly equal to the magnitude of the change in momentum of the larger mass
object.
D) smaller than the magnitude of the change in momentum of the larger mass object,
but not zero.
E) There is not enough information to answer the question.
16) A very light Ping-Pong ball moving east at a speed of 4 m/s collides with a very heavy
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stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling
ball moves very slowly to the east. On which object is the greater magnitude impulse
exerted during the collision?
A) On the bowling ball
B) On the Ping-Pong ball
C) Neither; the same magnitude impulse was exerted on both.
D) It is impossible to tell since the actual mass values are not given.
E) It is impossible to tell since the velocities after the collision are unknown.
17) A small car meshes with a large truck in a head-on collision. Which of the following
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statements concerning the magnitude of the average force during the collision is
correct?
A) There is the same magnitude average force exerted on both the small car and the
truck.
B) There is a greater average force exerted on the small car.
C) There is a greater average force exerted on the truck.
D) The force exerted on each object is directly proportional to its mass.
E) The force exerted on each object is inversely proportional to its mass.
18) A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg
ball moving northward at 2.0 m/s. What is the magnitude of the momentum of this
system just after the collision?
A) 8.0 kg m/s
B) 14 kg m/s
C) 10 kg m/s
D) 6.0 kg m/s
E) 2.0 kg m/s
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Answer Key
Testname: UNTITLED1
1) B
2) C, D
3) E
4) C
5) A
6) A
7) B
8) D
9) C
10) B
11) B, D
12) D
13) A
14) C
15) C
16) C
17) A
18) C
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