Physics 101 Quiz Momentum, Kinematics, Collisions,

1
Momentum
____ 1. A ball with original momentum +4.0 kgm/s hits a wall and bounces straight back without losing any kinetic
energy. The change in momentum of the ball is:
a. 0. c. 8.0 kgm/s.
b. 4.0 kgm/s. d. 8.0 kgm/s.
____ 2. A 75-kg swimmer dives horizontally off a 500-kg raft. The diver's speed immediately after leaving the raft is
4.0 m/s. A micro-sensor system attached to the edge of the raft measures the time interval during which the
diver applies an impulse to the raft just prior to leaving the raft surface. If the time interval is read as 0.20 s,
what is the magnitude of the average horizontal force by diver on the raft?
a. 900 N c. 525 N
b. 450 N d. 1 500 N
____ 3. A 0.12-kg ball is moving at 6 m/s when it is hit by a bat, causing it to reverse direction and have a speed of 14
m/s. What is the change in the magnitude of the momentum of the ball?
a. 0.39 kgm/s c. 1.3 kgm/s
b. 0.42 kgm/s d. 2.4 kgm/s
____ 4. Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s, and just
after is 3.5 m/s. What is the change in the magnitude of the ball's momentum?
a. 0.09 kgm/s c. 4.3 kgm/s
b. 1.5 kgm/s d. 126 kgm/s
____ 5. Alex throws a 0.15-kg rubber ball down onto the floor. The ball's speed just before impact is 6.5 m/s, and just
after is 3.5 m/s. If the ball is in contact with the floor for 0.025 s, what is the magnitude of the average force
applied by the floor on the ball?
a. 60 N c. 3.0 N
b. 133 N d. 3.5 N
____ 6. A crane drops a 0.30 kg steel ball onto a steel plate. The ball's speeds just before impact and after are 4.5 m/s
and 4.2 m/s, respectively. If the ball is in contact with the plate for 0.030 s, what is the magnitude of the
average force that the ball exerts on the plate during impact?
a. 87 N c. 3.0 N
b. 133 N d. 3.5 N
____ 7. Jerome pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted
straight back to Jerome with a return speed of 60 m/s. What is the magnitude of change in the ball's
momentum?
a. 4.0 kgm/s c. 18 kgm/s
b. 8.0 kgm/s d. 20 kgm/s
____ 8. Lonnie pitches a baseball of mass 0.20 kg. The ball arrives at home plate with a speed of 40 m/s and is batted
straight back to Lonnie with a return speed of 60 m/s. If the bat is in contact with the ball for 0.050 s, what is
the impulse experienced by the ball?
a. 360 Ns c. 400 Ns
b. 20 Ns d. 9.0 Ns2
____ 9. A car wash nozzle directs a steady stream of water at 1.5 kg/s, with a speed of 30 m/s, against a car window.
What force does the water exert on the glass? Assume the water does not splash back.
a. 11 N c. 110 N
b. 45 N d. 440 N
____ 10. A 75-kg swimmer dives horizontally off a 500-kg raft. If the diver's speed immediately after leaving the raft is
4 m/s, what is the corresponding raft speed?
a. 0.2 m/s c. 0.6 m/s
b. 0.5 m/s d. 4.0 m/s
____ 11. A cannon of mass 1 500 kg fires a 10-kg shell with a velocity of 200 m/s at an angle of 45 above the
horizontal. Find the recoil velocity of the cannon across the level ground.
a. 1.33 m/s c. 2.41 m/s
b. 0.94 m/s d. 1.94 m/s
____ 12. A machine gun is attached to a railroad flatcar that rolls with negligible friction. If the railroad car has a mass
of 6.25  10
4
 kg, how many bullets of mass 25 g would have to be fired at 250 m/s off the back to give the
railroad car a forward velocity of 0.5 m/s?
a. 400 c. 3 000
b. 2 000 d. 5 000
____ 13. Ann the Astronaut weighs 60 kg. She is space walking outside the space shuttle and pushes a 350-kg satellite
away from the shuttle at 0.90 m/s. What speed does this give Ann as she moves toward the shuttle?
a. 4.0 m/s c. 8.5 m/s
b. 5.3 m/s d. 9.0 m/s
____ 14. A miniature spring-loaded, radio-controlled gun is mounted on an air puck. The gun's bullet has a mass of
5.00 g, and the gun and puck have a combined mass of 120 g. With the system initially at rest, the radio
controlled trigger releases the bullet causing the puck and empty gun to move with a speed of 0.500 m/s.
What is the bullet's speed?
a. 4.80 m/s c. 48.0 m/s
b. 11.5 m/s d. 12.0 m/s
____ 15. A uranium nucleus (mass 238 units) at rest decays into a helium nucleus (mass 4.0 units) and a thorium
nucleus (mass 234 units). If the speed of the helium nucleus is 6.0  10
5
 m/s, what is the speed of the thorium
nucleus?
a. 1.0  10
4
 m/s c. 3.6  10
4
 m/s
b. 3.0  10
4
m/s d. 4.1  10
4
 m/s
____ 16. A 20-g bullet moving at 1 000 m/s is fired through a one-kg block of wood emerging at a speed of 100 m/s. If
the block had been originally at rest and is free to move, what is its resulting speed?
a. 9 m/s c. 90 m/s
b. 18 m/s d. 900 m/s
____ 17. A 20-g bullet moving at 1 000 m/s is fired through a one-kg block of wood emerging at a speed of 100 m/s.
What is the kinetic energy of the block that results from the collision if the block had not been moving prior
to the collision and was free to move?
a. 10 kJ c. 0.16 kJ
b. 9.8 kJ d. 0.018 kJ3
____ 18. A billiard ball is moving in the x-direction at 30.0 cm/s and strikes another billiard ball moving in the
y-direction at 40.0 cm/s. As a result of the collision, the first ball moves at 50.0 cm/s, and the second ball
stops. In what final direction does the first ball move?
a. in the x-direction c. at an angle of 45.0 ccw from the
x-direction
b. at an angle of 53.1 ccw from the
x-direction
d. Such a collision cannot happen.
____ 19. During a snowball fight two balls with masses of 0.4 and 0.6 kg, respectively, are thrown in such a manner
that they meet head-on and combine to form a single mass. The magnitude of initial velocity for each is 15
m/s. What is the speed of the 1.0-kg mass immediately after collision?
a. zero c. 6 m/s
b. 3 m/s d. 9 m/s
____ 20. A 2 500-kg truck moving at 10.00 m/s strikes a car waiting at a traffic light, hooking bumpers. The two
continue to move together at 7.00 m/s. What was the mass of the struck car?
a. 1 730 kg c. 1 200 kg
b. 1 550 kg d. 1 070 kg
____ 21. A 0.10-kg object moving initially with a velocity of +0.20 m/s makes an elastic head-on collision with a
0.15-kg object initially at rest. What percentage of the original kinetic energy is retained by the 0.10-kg
object?
a. 4% c. 50%
b. 4% d. 96%
____ 22. Two billiard balls have velocities of 2.0 m/s and 1.0 m/s when they meet in an elastic head-on collision.
What is the final velocity of the first ball after collision?
a. 2.0 m/s c. 0.5 m/s
b. 1.0 m/s d. +1.0 m/s
____ 23. Two objects, one less massive than the other, collide elastically and bounce back after the collision. If the two
originally had velocities that were equal in size but opposite in direction, then which one will be moving
faster after the collision?
a. The less massive one. c. The speeds will be the same after the
collision.
b. The more massive one. d. There is no way to be sure without the
actual masses.
____ 24. A 7.0-kg bowling ball strikes a 2.0-kg pin. The pin flies forward with a velocity of 6.0 m/s; the ball continues
forward at 4.0 m/s. What was the original velocity of the ball?
a. 4.0 m/s c. 6.6 m/s
b. 5.7 m/s d. 3.3 m/s
____ 25. Two skaters, both of mass 75 kg, are on skates on a frictionless ice pond. One skater throws a 0.3-kg ball at 5
m/s to his friend, who catches it and throws it back at 5 m/s. When the first skater has caught the returned ball,
what is the velocity of each of the two skaters?
a. 0.02 m/s, moving apart c. 0.02 m/s, moving towards each other
b. 0.04 m/s, moving apart d. 0.04 m/s, moving towards each other4
____ 26. A 90-kg halfback running north with a speed of 10 m/s is tackled by a 120-kg opponent running south at 4
m/s. The collision is perfectly inelastic. Compute the velocity of the two players just after the tackle.
a. 3 m/s south c. 2 m/s north
b. 2 m/s south d. 3 m/s north
____ 27. Popeye, of mass 70 kg, has just downed a can of spinach. He accelerates quickly and stops Bluto, of mass 700
kg (Bluto is very dense), who is charging in at 10 m/s. What was Popeye's speed?
a. 10 m/s c. 50 m/s
b. 31 m/s d. 100 m/s
____ 28. Two identical 7-kg bowling balls roll toward each other. The one on the left is moving at +4 m/s while the
one on the right is moving at 4 m/s. What is the velocity of each ball after they collide elastically?
a. Neither is moving. c. +4 m/s, 4 m/s
b. 4 m/s, +4 m/s d. 14 m/s, 14 m/s
____ 29. A 5-kg object is moving to the right at 4 m/s and collides with a 4-kg object moving to the left at 5 m/s. The
objects collide and stick together. After the collision, the combined object:
a. has the same kinetic energy that the
system had before the collision.
c. has no kinetic energy.
b. has more kinetic energy than the system
had before the collision.
d. has less momentum than the system had
before the collision.
____ 30. A model car is propelled by a cylinder of carbon dioxide gas. The cylinder emits gas at a rate of 4.5 g/s with
an exit speed of 80.0 m/s. The car has a mass of 400 g, including the CO2 cylinder. Starting from rest, what is
the car's initial acceleration?
a. 0.90 m/s
2
c. 9.0 m/s
2
b. 4.5 m/s
2
d. 36 m/s
2
____ 31. A 1 000-kg experimental rocket sled on level frictionless rails is loaded with 50 kg of propellant. It exhausts
the propellant in a 20-s "burn." If the rocket, initially at rest, moves at 150 m/s after the burn, what impulse is
experienced by the rocket sled?
a. 1.1  10
5
 kgm/s c. 1.5  10
5
 kgm/s
b. 1.6  10
5
 kgm/s d. 1.9  10
5
 kgm/s
____ 32. A 1 000-kg experimental rocket sled at rest on level frictionless rails is loaded with 50 kg of propellant. It
exhausts the propellant in a 20-s "burn." The rocket moves at 150 m/s after the burn. What average force is
experienced by the rocket during the burn?
a. 0.95  10
4
 N c. 0.60  10
4
N
b. 0.75  10
4
 N d. 0.35  10
4
 N
____ 33. A helicopter stays aloft by pushing large quantities of air downward every second. What mass of air must be
pushed downward at 40.0 m/s every second to keep a 1 000-kg helicopter aloft?
a. 120 kg c. 360 kg
b. 245 kg d. 490 kg
____ 34. At liftoff, the engines of the Saturn V rocket consumed 13 000 kg/s of fuel and exhausted the combustion
products at 2 900 m/s. What was the total upward force (thrust) provided by the engines?
a. 3.77  10
7
 N c. 1.47  10
8
 N
b. 7.54  10
7
N d. 2.95  10
8
N5
____ 35. A rocket of total mass M and with burnout mass 0.20 M attains a speed of 3 200 m/s after starting from rest in
deep space. What is the exhaust velocity of the rocket?
a. 1 000 m/s c. 3 000 m/s
b. 2 000 m/s d. 4 000 m/s
____ 36. Two masses collide and stick together. Before the collision one of the masses was at rest. Is there a situation
in which the kinetic energy is conserved in such a collision?
a. Yes, if the less massive particle is the one
initially at rest.
c. Yes, if the two particles have the same
mass.
b. Yes, if the more massive particle is the
one initially at rest.
d. No, kinetic energy is always lost is such a
collision.
____ 37. In an automobile collision, how does an airbag lessen the blow to the passenger? Assume as a result of the
collision, the passenger stops.
a. The air bag decreases the momentum
change of the passenger in the collision.
c. The stopping impulse is the same for
either the hard objects or the airbag.
Unlike the windshield or dashboard, the
air bag gives some increasing the time for
the slowing process and thus decreasing
the average force on the passenger.
b. During the collision, the force from the
air bag is greater than would be the force
from the windshield or dashboard so the
passenger cannot hit the hard objects.
d. The airbag is there to insure the seatbelt
holds.
____ 38. Two masses m1 and m2, with m1 < m2, have momenta with equal magnitudes. How do their kinetic energies
compare?
a. KE1 < KE2 c. KE1 > KE2
b. KE1 = KE2 d. More information is needed.ID: A
1
Momentum
Answer Section
MULTIPLE CHOICE
 1. D
 2. D
 3. D
 4. B
 5. A
 6. A
 7. D
 8. B
 9. B
 10. C
 11. B
 12. D
 13. B
 14. D
 15. A
 16. B
 17. C
 18. B
 19. B
 20. D
 21. A
 22. B
 23. A
 24. B
 25. B
 26. C
 27. D
 28. B
 29. C
 30. A
 31. C
 32. B
 33. B
 34. A
 35. B
 36. D
 37. C
 38. C