Multiple Choice
Identify the
choice that best completes the statement or answers the question.
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1.
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When comparing the momentum of two moving objects, which of the following is
correct?
a. | The object with the higher velocity will have less momentum if the masses are
equal. | b. | The more massive object will have less momentum if its velocity is
greater. | c. | The less massive object will have less momentum if the velocities are the
same. | d. | The more massive object will have less momentum if the velocities are the
same. |
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2.
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A child with a mass of 23 kg rides a bike with a mass of 5.5 kg at a velocity of
4.5 m/s to the south. Compare the momentum of the child with the momentum of the bike.
a. | Both the child and the bike have the same momentum. | b. | The bike has a
greater momentum than the child. | c. | The child has a greater momentum than the
bike. | d. | Neither the child nor the bike has momentum. |
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3.
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Which of the following has the greatest momentum?
a. | a tortoise with a mass of 275 kg moving at a velocity of 0.55 m/s | b. | a hare with a mass
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 mass of 1.8 kg moving at a
velocity of 6.7 m/s |
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4.
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A person sitting in a chair with wheels stands up, causing the chair to roll
backward across the floor. The momentum of the chair
a. | was zero while stationary and increased when the person stood. | b. | was greatest while
the person sat in the chair. | c. | remained the same. | d. | was zero when the
person got out of the chair and increased while the person sat. |
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5.
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The change in an object’s momentum is equal to
a. | the product of the mass of the object and the time interval. | b. | the product of the
force applied to the object and the time interval. | c. | the time interval divided by the net external
force. | d. | the net external force divided by the time interval. |
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6.
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A ball with a momentum of 4.0 kg·m/s hits a wall
and bounces straight back without losing any kinetic energy. What is the change in the ball’s
momentum?
a. | –8.0 kg·m/s | c. | 0.0 kg·m/s | b. | –4.0 kg·m/s | d. | 8.0 kg·m/s |
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7.
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A 0.2 kg baseball is pitched with a velocity of 40 m/s and is then batted to the
pitcher with a velocity of 60 m/s. What is the magnitude of change in the ball’s
momentum?
a. | 2 kg·m/s | c. | 8 kg·m/s | b. | 4 kg·m/s | d. | 20 kg·m/s |
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8.
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Which of the following statements properly relates the variables in the equation
FDt = Dp?
a. | A large constant force changes an object’s momentum over a long time
interval. | b. | A large constant force acting over a long time interval causes a large change in
momentum. | c. | A large constant force changes an object’s momentum at various time
intervals. | d. | A large constant force does not necessarily cause a change in an object’s
momentum. |
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9.
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Two objects with different masses collide and bounce back after an elastic
collision. Before the collision, the two objects were moving at velocities equal in magnitude but
opposite in direction. After the collision,
a. | the less massive object had gained momentum. | b. | the more massive
object had gained momentum. | c. | both objects had the same
momentum. | d. | both objects lost momentum. |
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10.
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A soccer ball collides with another soccer ball at rest. The total momentum of
the balls
a. | is zero. | c. | remains constant. | b. | increases. | d. | decreases. |
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11.
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Two skaters stand facing each other. One skater’s mass is 60 kg, and the
other’s mass is 72 kg. If the skaters push away from each other without spinning,
a. | the lighter skater has less momentum. | b. | their momenta are equal but
opposite. | c. | their total momentum doubles. | d. | their total momentum
decreases. |
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12.
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Two swimmers relax close together on air mattresses in a pool. One
swimmer’s mass is 48 kg, and the other’s mass is 55 kg. If the swimmers push away from
each other,
a. | their total momentum triples. | c. | their total momentum
doubles. | b. | their momenta are equal but opposite. | d. | their total momentum
decreases. |
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13.
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In a two-body collision,
a. | momentum is always conserved. | b. | kinetic energy is always
conserved. | c. | neither momentum nor kinetic energy is conserved. | d. | both momentum and
kinetic energy are always conserved. |
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14.
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The law of conservation of momentum states that
a. | the total initial momentum of all objects interacting with one another usually equals
the total final momentum. | b. | the total initial momentum of all objects
interacting with one another does not equal the total final momentum. | c. | the total momentum
of all objects interacting with one another is zero. | d. | the total momentum of all objects interacting
with one another remains constant regardless of the nature of the forces between the
objects. |
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15.
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Two objects move separately after colliding, and both the total momentum and
total kinetic energy remain constant. Identify the type of collision.
a. | elastic | c. | inelastic | b. | nearly elastic | d. | perfectly
inelastic |
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16.
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Two objects stick together and move with a common velocity after colliding.
Identify the type of collision.
a. | elastic | c. | inelastic | b. | nearly elastic | d. | perfectly
inelastic |
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17.
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Two billiard balls collide. Identify the type of collision.
a. | elastic | c. | inelastic | b. | nearly elastic | d. | perfectly
inelastic |
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18.
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Two balls of dough collide and stick together. Identify the type of
collision.
a. | elastic | c. | inelastic | b. | nearly elastic | d. | perfectly
inelastic |
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19.
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In an inelastic collision between two objects with unequal masses,
a. | the total momentum of the system will increase. | b. | the total momentum
of the system will decrease. | c. | the kinetic energy of one object will increase
by the amount that the kinetic energy of the other object decreases. | d. | the momentum of one
object will increase by the amount that the momentum of the other object
decreases. |
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20.
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A billiard ball collides with a stationary identical billiard ball in an elastic
head-on collision. After the collision, which of the following is true of the first ball?
a. | It maintains its initial velocity. | c. | It comes to
rest. | b. | It has one-half its initial velocity. | d. | It moves in the opposite
direction. |
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Short Answer
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21.
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A 0.16 kg cue ball is traveling at 10.0 m/s toward a full rack of 15 billiard
balls. What is the magnitude of the total momentum of the system of 16 balls after the cue ball
strikes the rack?
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22.
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On a pool table, a moving cue ball collides with the eight ball, which is at
rest. Is it possible for both balls to be at rest after the collision? Use the law of conservation of
momentum to explain your reasoning.
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Problem
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23.
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Compare the momentum of a 6160 kg truck moving at 3.00 m/s to the momentum of a
1540 kg car moving at 12.0 m/s.
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24.
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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?
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25.
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A 6.0 ´ 10  kg
tennis ball moves at a speed 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 change in the ball’s momentum?
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26.
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A rubber ball with a mass of 0.30 kg is dropped onto a steel plate. The
ball’s speed just before impact is 4.5 m/s and just after impact is 4.2 m/s. What is the change
in the ball’s momentum?
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27.
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A baseball bat strikes a baseball with a force of 35 N. The bat is in contact
with the ball for 0.12 s. What is the magnitude of the change in momentum of the ball?
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28.
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A pool cue strikes a 0.16 kg billiard ball with a force of 15 N. The cue remains
in contact with the ball for 0.085 s. The ball was initially at rest. What is the final speed of the
ball?
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29.
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A player at first base catches a throw traveling 22 m/s. The baseball, which has
a mass of 0.21 kg, comes to a complete stop in the glove after 0.15 s. Assuming the force of the
glove was uniform, what force did the glove exert on the ball?
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30.
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A 65 kg trapeze artist falls straight down onto a safety net. The trapeze
artist’s initial speed as she hits the net is 9.9 m/s, and the net stretches 1.5 m vertically
as she comes to a stop. What average net force does the trapeze artist experience while the net
breaks her fall? How many “g’s” of acceleration does she experience on average? (1
g = 9.81 m/s  )
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A 68.0 kg diver jumps off a diving platform, rises about 1 m above the platform,
then falls to the pool.
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31.
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What is the diver’s momentum at her highest point in the dive?
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32.
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Use the impulse-momentum theorem to find the diver’s momentum after
falling for 1.00 s.
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33.
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The diver strikes the water at a speed of 14.7 m/s, then slows to a stop
underwater in 0.35 s. What force does the water exert on the diver?
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34.
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A train with a mass of 1.8 ´ 10  kg is moving at 15 m/s when the engineer applies the brakes. If the braking force
is constant at 3.5 ´ 10  N, how long does it
take the train to stop? How far does the train travel during this time?
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35.
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An astronaut with a mass of 85 kg is outside a space capsule when the tether
line breaks. 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?
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36.
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A swimmer with a mass of 75 kg dives off a raft with a mass of 500 kg. If the
swimmer’s speed is 4 m/s immediately after leaving the raft, what is the speed of the
raft?
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37.
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A bullet with a mass of 5.00 ´ 10  kg is loaded into a gun. The loaded gun has a mass of 0.52 kg. The bullet is fired,
causing the empty gun to recoil at a speed of 2.1 m/s. What is the speed of the bullet?
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38.
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A 65.0 kg ice-skater standing on frictionless ice throws a 0.15 kg snowball
horizontally at a speed of 32.0 m/s. At what speed does the skater move backward?
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39.
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Two ice-skaters, each with a mass of 50 kg, are stationary on a frictionless ice
pond. One skater throws a 0.2 kg ball at 5 m/s to the other skater, who catches it. What are the
velocities of the skaters when the ball is caught?
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40.
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A bullet with a mass of 6.00 g is fired through a 1.25 kg block of wood on a
frictionless surface. The initial speed of the bullet is 896 m/s, and the speed of the bullet after
it exits the block is 435 m/s. At what speed does the block move after the bullet passes through
it?
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41.
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A 0.10 kg object makes an elastic head-on collision with a 0.15 kg stationary
object. The final velocity of the 0.10 kg object after the collision is 0.045 m/s in the direction
opposite its initial movement. The final velocity of the 0.15 kg object after the collision is 0.16
m/s in the same direction as the object which strikes it. What was the initial velocity of the 0.10
kg object?
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42.
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A 15 g marble moves to the right at 3.6 m/s and makes an elastic head-on
collision with a 22 g marble. The final velocity of the 15 g marble is 5.4 m/s to the left, and the
final velocity of the 22 g marble is 2.0 m/s to the right. What was the initial velocity of the 22 g
marble?
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