# Quiz 9: Momentum

Physics & Astronomy

Q 1Q 1

A rubber ball and a lump of clay have equal mass. They are thrown with equal speed 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 experiences the greater momentum change?
A)the ball
B)the clay
C)Both of them experience the same non-zero momentum change.
D)Both of them experience zero momentum change.

Free

Multiple Choice

A

Q 2Q 2

Which of the following quantities are units of momentum? (There could be more than one correct choice.)
A)N ∙ m
B)kg ∙ s/m
C)kg ∙ m/s
D)N ∙ s
E)kg ∙ m

^{2}/s^{2}Free

Multiple Choice

C, D

Q 3Q 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)
B)2
C)4
D)8
E)16

Free

Multiple Choice

C

Q 4Q 4

A very elastic rubber ball is dropped from a certain height and hits the floor with a 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 had the same momentum just before and just after the bounce.
B)The magnitude of the ball's momentum was the same just before and just after the bounce.
C)The ball's momentum was conserved during the bounce.
D)None of the above statements are correct.

Free

Multiple Choice

Q 5Q 5

The momentum of an isolated system is conserved
A)only in inelastic collisions.
B)only in elastic collisions.
C)in both elastic and inelastic collisions.

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Multiple Choice

Q 6Q 6

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)moving backward.
B)stationary.
C)moving forward.

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Multiple Choice

Q 7Q 7

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball 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)Catch the ball.
B)Deflect the ball back.
C)Your final speed on the skateboard will be the same regardless whether you catch the ball or deflect the ball.

Free

Multiple Choice

Q 8Q 8

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the momentum change during the collision is correct? (There could be more than one correct choice.)
A)The truck experiences the greater magnitude momentum change.
B)The small car experiences the greater magnitude momentum change.
C)The small car and the truck experience the same magnitude momentum change.
D)The magnitude of the momentum change experienced by each one is inversely proportional to its mass.
E)The magnitude of the momentum change experienced by each one is directly proportional to its mass.

Free

Multiple Choice

Q 9Q 9

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the momentum during the collision are correct? (There could be more than one correct choice.)
A)The momentum of the truck is conserved.
B)The momentum of the car is conserved.
C)The car and the truck must undergo the same change in speed.
D)The momentum of the car and the momentum of the truck are each conserved.
E)The momentum of the car-truck system is conserved, but the momentum of each one separately is not conserved.

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Multiple Choice

Q 10Q 10

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 on your car?
A)hitting the other car
B)hitting the brick wall
C)The force would be the same in both cases.
D)None of the above choices are correct.

Free

Multiple Choice

Q 11Q 11

A rocket explodes into two fragments, one 25 times heavier than the other. The magnitude of the momentum change of the lighter fragment is
A)25 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)5 times as great as the momentum change of the heavier fragment.
E)1/4 as great as the momentum change of the heavier fragment.

Free

Multiple Choice

Q 12Q 12

Which of the following quantities are units of impulse? (There could be more than one correct choice.)
A)N ∙ m
B)kg ∙ s/m
C)kg ∙ m/s
D)N ∙ s
E)kg ∙ m

^{2}/s^{2}Free

Multiple Choice

Q 13Q 13

Three cars, car X, car Y, and car Z, begin accelerating from rest at the same time. Car X 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)They all have the same amount of momentum.
B)Car X
C)Car Y
D)Car Z

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Multiple Choice

Q 14Q 14

During World War I, Germany used a "Big Bertha" cannon to hurl shells into Paris 30 miles away. This gun also had a very long barrel. What was the reason for using a long barrel in these guns?
A)to exert a larger force on the shells
B)to reduce frictional losses
C)to allow the force of the expanding gases from the gunpowder to act for a longer time
D)to increase the force exerted on the bullet due to the expanding gases from the gunpowder
E)to reduce the force exerted on the bullet due to the expanding gases from the gunpowder

Free

Multiple Choice

Q 15Q 15

In a collision between two unequal masses, which mass receives a greater magnitude impulse?
A)the larger mass
B)the smaller mass
C)They receive equal impulses.

Free

Multiple Choice

Q 16Q 16

Identical forces act for the same length of time on two different objects. The magnitude of the change in momentum of the lighter object is
A)smaller than the magnitude of the change in momentum of the larger mass, but not zero.
B)larger than the magnitude of the change in momentum of the larger mass.
C)exactly equal to the magnitude of the change in momentum of the larger mass.
D)zero.
E)There is not enough information to answer the question.

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Multiple Choice

Q 17Q 17

A very light ping-pong ball moving east at a speed of 4 m/s collides with a very heavy stationary bowling ball. The Ping-Pong ball bounces back to the west, and the bowling ball moves very slowly to the east. Which object experiences the greater magnitude impulse during the collision?
A)Neither; both experienced the same magnitude impulse.
B)the Ping-Pong ball
C)the bowling ball
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.

Free

Multiple Choice

Q 18Q 18

A small car meshes with a large truck in a head-on collision. Which of the following statements concerning the magnitude of the average force during the collision is correct?
A)The truck experiences the greater average force.
B)The small car experiences the greater average force.
C)The small car and the truck experience the same average force.
D)The force experienced by each one is inversely proportional to its mass.
E)The force experienced by each one is directly proportional to its mass.

Free

Multiple Choice

Q 19Q 19

In an inelastic collision involving an isolated system, the final total momentum is
A)exactly the same as the initial momentum.
B)more than the initial momentum.
C)less than the initial momentum.

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Multiple Choice

Q 20Q 20

A 5-kg ball collides inelastically head-on with a 10-kg ball, which is initially stationary. Which of the following statements is true? (There could be more than one correct choice.)
A)The magnitude of the change of velocity the 5-kg ball experiences is greater than that of the 10-kg ball.
B)The magnitude of the change of velocity the 5-kg ball experiences is less than that of the 10-kg ball.
C)The magnitude of the change of velocity the 5-kg ball experiences is equal to that of the 10-kg ball.
D)The magnitude of the change of the momentum of the 5-kg ball is equal to the magnitude of the change of momentum of the 10-kg ball.
E)Both balls lose all their momentum since the collision is inelastic.

Free

Multiple Choice

Q 21Q 21

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)14 kg ∙ m/s
B)2.0 kg ∙ m/s
C)10 kg ∙ m/s
D)6.0 kg ∙ m/s
E)8.0 kg ∙ m/s

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Multiple Choice

Q 22Q 22

A person sits on a freely spinning lab stool that has no friction in its axle. When this person extends her arms,
A)her moment of inertia decreases and her angular speed increases.
B)her moment of inertia decreases and her angular speed decreases.
C)her moment of inertia increases and her angular speed increases.
D)her moment of inertia increases and her angular speed decreases.
E)her moment of inertia increases and her angular speed remains the same.

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Multiple Choice

Q 23Q 23

A merry-go-round spins freely when Diego moves quickly to the center along a radius of the merry-go-round. As he does this, it is true to say that
A)the moment of inertia of the system decreases and the angular speed increases.
B)the moment of inertia of the system decreases and the angular speed decreases.
C)the moment of inertia of the system decreases and the angular speed remains the same.
D)the moment of inertia of the system increases and the angular speed increases.
E)the moment of inertia of the system increases and the angular speed decreases.

Free

Multiple Choice

Free

Essay

Q 25Q 25

A 0.14-kg baseball is dropped from rest from a height of 2.0 m above the ground. What is the magnitude of its momentum just before it hits the ground if we neglect air resistance?
A)0.28 kg ∙ m/s
B)0.88 kg ∙ m/s
C)0.44 kg ∙ m/s
D)0.62 kg ∙ m/s
E)1.4 kg ∙ m/s

Free

Multiple Choice

Q 26Q 26

Three objects are moving along a straight line as shown in the figure. Taking the positive direction to be to the right, what is the total momentum of this system?
A)+106 kg ∙ m/s
B)-106 kg ∙ m/s
C)+14.0 kg ∙ m/s
D)-14.0 kg ∙ m/s
E)0.00 kg ∙ m/s

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Multiple Choice

Q 27Q 27

A 0.330-kg volleyball is thrown vertically downward with a speed of 0.150 m/s in a place where g = 9.81 m/s

^{2}. It takes it 0.0655 s to reach the ground. What is the magnitude of its momentum just before it hits the ground? A)0.212 kg ∙ m/s B)0.262 kg ∙ m/s C)0.163 kg ∙ m/s D)0.0216 kg ∙ m/s E)0.0418 kg ∙ m/sFree

Multiple Choice

Q 28Q 28

Two air track carts move along an air track towards each other. Cart A has a mass of 450 g and moves toward the right with a speed of 0.850 m/s. Cart B has a mass of 300 g and moves toward the left with a speed of 1.12 m/s. What is the total momentum of the two-cart system?
A)0.047 kg ∙ m/s toward the right
B)0.719 kg ∙ m/s toward the right
C)0.719 kg ∙ m/s toward the left
D)0.750 kg ∙ m/s toward the right
E)0.750 kg ∙ m/s toward the left

Free

Multiple Choice

Q 29Q 29

A 100-g ball falls from a window that is 12 m above ground level and experiences no significant air resistance as it falls. What is its momentum when it strikes the ground?
A)3.3 kg ∙ m/s
B)4.8 kg ∙ m/s
C)1.8 kg ∙ m/s
D)1.5 kg ∙ m/s
E)2.4 kg ∙ m/s

Free

Multiple Choice

Q 30Q 30

A 0.140-kg baseball is dropped and reaches a speed of 1.20 m/s just before it hits the ground and bounces. It rebounds with an upward velocity of 1.00 m/s. What is the change of the ball's momentum during the bounce?
A)0.0280 kg ∙ m/s upwards
B)0.0280 kg ∙ m/s downwards
C)0.308 kg ∙ m/s upwards
D)0.308 kg ∙ m/s downwards
E)0.000 kg ∙ m/s

Free

Multiple Choice

Q 31Q 31

A firecracker breaks up into two pieces, one of which has a mass of 200 g and flies off along the +x-axis with a speed of 82.0 m/s. The second piece has a mass of 300 g and flies off along the +y-axis with a speed of 45.0 m/s. What is the total momentum of the two pieces?
A)361 kg ∙ m/s at 56.3° from the +x-axis
B)93.5 kg ∙ m/s at 28.8° from the +x-axis
C)21.2 kg ∙ m/s at 39.5° from the +x-axis
D)361 kg ∙ m/s at 0.983° from the +x-axis
E)21.2 kg ∙ m/s at 56.3° from the +x-axis

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Multiple Choice

Q 32Q 32

Find the magnitude and direction of the net momentum of the system shown in the figure. Express the direction by giving the angle the net momentum makes with the +x-axis.

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Essay

Q 33Q 33

A 600-kg car makes a 90° turn. Its speed before the turn is 21.0 m/s and after the turn it is 24.0 m/s. What is the magnitude of the change in the car's momentum during the turn?
A)19.1 × 10

^{3}kg∙m/s B)10.2 × 10^{3}kg∙m/s C)9.55 × 10^{3}kg∙m/s D)12.0 × 10^{3}kg∙m/s E)22.2 × 10^{3}kg∙m/sFree

Multiple Choice

Q 34Q 34

A 0.10-kg ball, traveling horizontally at 25 m/s, strikes a wall and rebounds at 19 m/s. What is the magnitude of the change in the momentum of the ball during the rebound?
A)1.2 kg ∙ m/s
B)1.8 kg ∙ m/s
C)4.4 kg ∙ m/s
D)5.4 kg ∙ m/s
E)72 kg ∙ m/s

Free

Multiple Choice

Q 35Q 35

A 60-kg swimmer suddenly dives horizontally from a 150-kg raft with a speed of 1.5 m/s. The raft is initially at rest. What is the speed of the raft immediately after the diver jumps if the water has negligible effect on the raft?

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Essay

Q 36Q 36

A 14,000-kg boxcar is coasting at 1.50 m/s along a horizontal track when it suddenly hits and couples with a stationary 10,000-kg boxcar. What is the speed of the cars just after the collision?

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Essay

Q 37Q 37

In a police ballistics test, 2.00-g bullet traveling at 700 m/s suddenly hits and becomes embedded in a stationary 5.00-kg wood block. What is the speed of the block immediately after the bullet has stopped moving relative to the block?

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Essay

Q 38Q 38

A 328-kg car moving at 19.1 m/s in the +x direction hits from behind a second car moving at in the same direction. If the second car has a mass of and a speed of right after the collision, what is the velocity of the first car after this sudden collision?
A)14.0 m/s
B)18.2 m/s
C)24.2 m/s
D)-14.0 m/s

Free

Multiple Choice

Q 39Q 39

A 1200-kg ore cart is rolling at 10.8 m/s across a flat friction-free surface. A crane suddenly drops of ore vertically into the cart. How fast does the cart move just after being loaded with the ore?
A)6.30 m/s
B)3.80 m/s
C)4.20 m/s
D)5.70 m/s

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Multiple Choice

Q 40Q 40

An empty train car of mass 2.0 x 10

^{4}kg coasts along at 10 m/s. A 3000-kg boulder is suddenly dropped vertically into the car. Find the speed of the car immediately after the boulder is dropped in.Free

Essay

Q 41Q 41

Two ice skaters suddenly push off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire relative to the ice?
A)0.50 m/s
B)0.28 m/s
C)0.38 m/s
D)0.75 m/s
E)0.00 m/s

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Multiple Choice

Q 42Q 42

A 1200-kg cannon suddenly fires a cannonball at What is the recoil speed of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.
A)2.9 m/s
B)35 m/s
C)3.5 m/s
D)3.2 m/s

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Multiple Choice

Q 43Q 43

A dinner plate falls vertically to the floor and breaks up into three pieces, which slide horizontally along the floor. Immediately after the impact, a 200-g piece moves along the +x-axis with a speed of 2.00 m/s, a 235-g piece moves along the +y-axis with a speed of 1.50 m/s. The third piece has a mass of 100 g. What is the speed of the third piece?
A)2.51 m/s
B)2.57 m/s
C)3.50 m/s
D)5.33 m/s
E)6.83 m/s

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Multiple Choice

Q 44Q 44

A dinner plate falls vertically to the floor and breaks up into three pieces, which slide horizontally along the floor. Immediately after the impact, a 320-g piece moves along the +x-axis with a speed of 2.00 m/s and a 355-g piece moves along the +y-axis with a speed of 1.50 m/s. The third piece has a mass of 100 g. In what direction relative to the +x-axis does the third piece move?
A)216.9° from the +x-axis
B)219.8° from the +x-axis
C)36.9° from the +x-axis
D)39.9° from the +x-axis
E)39.8° from the +x-axis

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Multiple Choice

Q 45Q 45

In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges?
A)1.50 m/s
B)2.97 m/s
C)3.00 m/s
D)273 m/s

Free

Multiple Choice

Q 46Q 46

Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. What is their separation after the heavier astronaut has moved 12 m?
A)9.0 m
B)16 m
C)21 m
D)24 m
E)28 m

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Multiple Choice

Q 47Q 47

Two astronauts, of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. How far has the heavier astronaut moved when the lighter astronaut has moved 12 m?
A)16 m
B)9.0 m
C)21 m
D)7.0 m
E)12 m

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Multiple Choice

Q 48Q 48

Astronaut Jennifer's lifeline to her spaceship comes loose and she finds herself stranded, "floating" 100 m from the mothership. She suddenly throws her 2.00-kg wrench at 20 m/s in a direction away from the ship. If she and her spacesuit have a combined mass of 200 kg, how long does it take her to coast back to her spaceship?
A)1000 s
B)750 s
C)500 s
D)250 s
E)2.50 min

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Multiple Choice

Q 49Q 49

A 14-cm diameter champagne bottle rests on its side on top of a frictionless horizontal table. Suddenly, the cork pops and the bottle slides backward, covering a distance of in If the mass of the bottle is 500 times the mass of the cork, find the distance from the original position that the cork will land on the table. Neglect air resistance and assume that the cork is very small compared to the bottle.
A)3000 cm
B)60 m
C)85 m
D)8.5 cm

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Multiple Choice

Q 50Q 50

The graph in the figure shows the x component F of the net force that acts for 10 s on a 100-kg crate. What is the change in the momentum of the crate during the 10 s that this force acts?
A)-100 kg ∙ m/s
B)-25 kg ∙ m/s
C)75 kg ∙ m/s
D)-75 kg ∙ m/s
E)25 kg ∙ m/s

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Multiple Choice

Q 51Q 51

A forklift pushes a 100-kg crate, starting from rest, with a horizontal force of magnitude F. The graph in the figure shows the x component of this force as a function of time. What is the instantaneous velocity of the crate at time t = 10 s?
A)25 cm/s
B)0.00 cm/s
C)75 cm/s
D)-25 cm/s
E)-75 cm/s

Free

Multiple Choice

Q 52Q 52

A batter applies an average force of 8000 N to a baseball for 1.1 ms. What is the magnitude of the impulse delivered to the baseball by the bat?

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Essay

Q 53Q 53

A batter hits a 0.140-kg baseball that was approaching him at 30 m/s and, as a result, the ball leaves the bat at 40 m/s in the reverse of its original direction. The ball remains in contact with the bat for 2.0 ms. What is the magnitude of the average force exerted by the bat on the ball?

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Essay

Q 54Q 54

Jennifer hits a stationary 0.20-kg ball, and it leaves her racket at 40 m/s. Time-lapse photography shows that the ball was in contact with the racket for 40 ms.
(a)What average force did the ball exert on the racket?
(b)What is the ratio of this force to the weight of the ball?

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Essay

Q 55Q 55

A 0.17-kg baseball is thrown with a speed of 38 m/s and it is hit straight back toward the pitcher with a speed of 62 m/s. What is the magnitude of the impulse exerted upon the ball by the bat?

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Essay

Q 56Q 56

A super dart of mass 20 g, traveling at 350 m/s, strikes a steel plate at an angle of 30° with the plane of the plate, as shown in the figure. It bounces off the plate at the same angle but at a speed of 320 m/s. What is the magnitude of the impulse that the plate gives to the bullet?
A)0.52 N ∙ s
B)4.3 N ∙ s
C)300 N ∙ s
D)6.7 N ∙ s
E)0.30 N ∙ s

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Multiple Choice

Q 57Q 57

A golf club exerts an average horizontal force of 1000 N on a 0.045-kg golf ball that is initially at rest on the tee. The club is in contact with the ball for 1.8 ms. What is the speed of the golf ball just as it leaves the tee?
A)30 m/s
B)35 m/s
C)40 m/s
D)45 m/s
E)50 m/s

Free

Multiple Choice

Q 58Q 58

A 0.140-kg baseball is thrown with a velocity of It is struck by the bat with an average force of 5000 N, which results in a velocity of 37.0 m/s in the opposite direction from the original velocity. How long were the bat and ball in contact?
A)1.79 × 10

^{-3}s B)1.28 × 10^{-2}s C)3.07 × 10^{-2}s D)4.30 × 10^{-3}sFree

Multiple Choice

Q 59Q 59

Calculate the impulse due to a force of that lasts for
A)6.3 kg∙ m/s
B)5.0 kg∙ m/s
C)5.7 kg∙ m/s
D)6.9 kg∙ m/s

Free

Multiple Choice

Q 60Q 60

A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of and it bounces back with this same speed. The ball is in contact with the wall What is the magnitude of the average force exerted on the wall by the ball?
A)800 N
B)400 N
C)55,000 N
D)27,500 N
E)13,750 N

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Multiple Choice

Q 61Q 61

A 475-gram ball is traveling horizontally at 12.0 m/s to the left when it is suddenly struck horizontally by a bat, causing it to reverse direction and initially travel at 8.50 m/s to the right. If the bat produced an average force of 1275 N on the ball, for how long (in milliseconds)was it in contact with the ball?

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Essay

Q 62Q 62

A 0.140 kg baseball is thrown horizontally with a velocity of 28.9 m/s. It is struck with a constant horizontal force that lasts for 1.85 ms, which results in a velocity of 37.0 m/s in the opposite direction. What was the magnitude of the horizontal force?
A)0.613 kN
B)2.19 kN
C)2.80 kN
D)4.99 kN

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Multiple Choice

Q 63Q 63

A golf ball of mass 0.050 kg is at rest on the tee. Just after being struck, it has a velocity of 102 m/s. If the club and ball were in contact for what is the average force exerted on the ball by the club?
A)6.3 kN
B)7.1 kN
C)5.5 kN
D)4.9 kN

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Multiple Choice

Q 64Q 64

A 0.24 kg blob of clay is thrown at a wall with an initial horizontal velocity of If the clay comes to a stop in what is the average horizontal force on the clay due to the wall?
A)42 N
B)26 N
C)35 N
D)51 N

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Multiple Choice

Q 65Q 65

A steady horizontal force lasting for 2.1 s gives a 1.25 kg object an acceleration of 3.2 m/s

^{2}on a frictionless table. What impulse does this force give to the object? A)26 kg ∙ m/s B)11 kg ∙ m/s C)8.4 kg ∙ m/s D)2.6 kg ∙ m/sFree

Multiple Choice

Q 66Q 66

A block of mass m = 34 kg and speed V is behind a block of mass M = 81 kg and speed of as shown in the figure. The surface is frictionless and the blocks collide and couple. After the collision, the blocks have a common speed of What is the magnitude of the impulse on the 34-kg block due to the collision?
A)32 N ∙ s
B)14 N ∙ s
C)41 N ∙ s
D)57 N ∙ s
E)73 N ∙ s

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Multiple Choice

Q 67Q 67

A very small 51-g steel ball is released from rest and falls vertically onto a steel plate. The ball strikes the plate and is in contact with it for 0.50 ms. The ball rebounds elastically and returns to its original height. The total time interval for a round trip is 3.00 s. What is the magnitude of the average force exerted on the ball by the plate during contact with the plate?
A)3000 N
B)1500 N
C)2490 N
D)2000 N
E)3500 N

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Multiple Choice

Q 68Q 68

A 0.140-kg baseball is dropped from rest. It has a speed of 1.20 m/s just before it hits the ground, and it rebounds with an upward speed of 1.00 m/s. The ball is in contact with the ground for 0.0140 s. What is the average force exerted by the ground on the ball during the time of contact?
A)2.00 N upwards
B)2.00 N downwards
C)22.0 N upwards
D)22.0 N downwards
E)0.00 N

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Multiple Choice

Q 69Q 69

A batter hits a foul ball. The 0.14-kg baseball that was approaching him at 40 m/s leaves the bat at 30 m/s in a direction perpendicular to the line between the batter and the pitcher. What is the magnitude of the impulse delivered to the baseball?
A)9.8 N ∙ s
B)1.4 N ∙ s
C)3.5 N ∙ s
D)5.6 N ∙ s
E)7.0 N ∙ s

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Multiple Choice

Q 70Q 70

A block of mass m = 5.6 kg, moving on a frictionless surface with a velocity of to the right, collides with a block of mass M at rest, as shown in the figure. After the collision, the 5.6-kg block recoils with a velocity of to the left. If the blocks are in contact for 0.20 s, what is the magnitude of the average force on the 5.6-kg block, while the two blocks are in contact?
A)202 N
B)192 N
C)182 N
D)0 N
E)0 N

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Multiple Choice

Q 71Q 71

A force of 5.3 N is needed to hold on to an umbrella in a strong wind. If the air molecules each have a mass of 4.7 ×10

^{-26}kg, and each one strikes the umbrella (without rebounding)with a speed of 2.0 m/s in the same direction, how many atoms strike the umbrella each second? Assume that the wind blows horizontally so that the gravity can be neglected.Free

Essay

Q 72Q 72

A fire hose is turned on the door of a burning building in order to knock the door down. This requires a force of 1000 N. If the hose delivers 40 kg of water per second, what is the minimum velocity of the stream needed to knock down the door, assuming the water doesn't bounce back?
A)15 m/s
B)20 m/s
C)25 m/s
D)30 m/s

Free

Multiple Choice

Q 73Q 73

A 2200-kg auto moving northward at 12.0 m/s runs into a 3800-kg truck which is also moving northward, but at 5.00 m/s. If the vehicles lock bumpers, how fast are they moving just after the collision?

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Q 74Q 74

A 1200-kg car moving at suddenly collides with a stationary car of mass If the two vehicles lock together, what is their combined velocity immediately after the collision?
A)6.9 m/s
B)8.6 m/s
C)12.1 m/s
D)5.5 m/s

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Multiple Choice

Q 75Q 75

A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the momentum of these two sea creatures just after their collision? You can neglect any drag effects of the water during the collision.
A)0.00 kg ∙ m/s
B)1200 kg ∙ m/s
C)2000 kg ∙ m/s
D)7200 kg ∙ m/s
E)6000 kg ∙ m/s

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Multiple Choice

Q 76Q 76

A 1000-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the speed of these two sea creatures just after their collision? You can neglect any drag effects of the water during the collision.
A)0.00 m/s
B)3.0 m/s
C)4.0 m/s
D)5.0 m/s
E)6.0 m/s

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Multiple Choice

Q 77Q 77

A 2.0-kg mass moving at 5.0 m/s suddenly collides head-on with a 3.0-kg mass at rest. If the collision is perfectly inelastic, what is the speed of the masses just after the collision?
A)10 m/s
B)2.5 m/s
C)2.0 m/s
D)0 m/s, since the collision is inelastic

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Multiple Choice

Q 78Q 78

An 80-kg man is skating northward and happens to suddenly collide with a 20-kg boy who is ice skating toward the east. Immediately after the collision, the man and boy are seen to be moving together at 2.5 m/s in a direction 60° north of east. How fast was the boy moving just before the collision?

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Essay

Q 79Q 79

A car (of mass 1500 kg)and a small truck (of mass 2000 kg)collide suddenly at right angles at an icy intersection. The car was originally traveling eastward at 20.0 m/s and the truck was traveling northward at 20.0 m/s just before the collision took place. What is the speed of the combined wreck just after the collision if the vehicles become enmeshed?

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Essay

Q 80Q 80

Two vehicles approach a right angle intersection and then suddenly collide. After the collision, they become entangled. If their mass ratios were 1:4 and their respective speeds as they approached the intersection were both 13 m/s, find the magnitude and direction of the final velocity of the wreck.
A)11 m/s at 14° with respect to the original direction of the lighter car
B)16 m/s at 76° with respect to the original direction of the lighter car
C)11 m/s at 76° with respect to the original direction of the lighter car
D)16 m/s at 14° with respect to the original direction of the lighter car

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Multiple Choice

Q 81Q 81

A car heading north suddenly collides at an intersection with a truck of the same mass heading east. If they lock together and travel at at 15° north of east just after the collision, how fast was the car initially traveling?
A)14 m/s
B)7 m/s
C)28 m/s
D)11 m/s

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Multiple Choice

Q 82Q 82

A puck with a mass m

_{1}= 50 g moving at 1.0 m/s approaches a stationary puck with a mass m_{2}= 100 g on a frictionless air table, and they undergo a sudden two-dimensional elastic collision. After the collision, both pucks have identical speeds, but travel in different directions. What is the angle between the original and final paths of puck with mass m_{1}? A)30° B)60° C)90° D)120° E)150°Free

Multiple Choice

Q 83Q 83

A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together after the collision. What is the speed of the wreckage just after the collision?
A)6.10 m/s
B)12.2 m/s
C)25.0 m/s
D)35.0 m/s
E)17.3 m/s

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Multiple Choice

Q 84Q 84

A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together after the collision. In what direction does the wreckage move just after the collision?
A)36.9° N of E
B)42.0° N of E
C)45.0° N of E
D)53.1° N of E
E)48.0° N of E

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Multiple Choice

Q 85Q 85

A 900-kg car traveling 30.0° south of east at 12.0 m/s suddenly collides with a 750-kg car traveling north at 17.0 m/s. The cars stick together after colliding. What is the speed of the wreckage just after the collision?
A)7.21 m/s
B)12.2 m/s
C)20.4 m/s
D)25.0 m/s
E)17.3 m/s

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Multiple Choice

Q 86Q 86

A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling at 60 km/h toward the south. The two cars stick together after the collision. What is the speed of the cars after collision?
A)8.3 m/s
B)14 m/s
C)17 m/s
D)22 m/s

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Multiple Choice

Q 87Q 87

A 1500-kg car traveling at 90 km/h toward the east suddenly collides with a 3000-kg car traveling at 60 km/h toward the south. The two cars stick together after the collision. What is the direction of motion of the cars after collision?
A)36.9° S of E
B)36.9° E of S
C)53.1° S of E
D)53.1° E of S

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Multiple Choice

Q 88Q 88

Two dogs, Rover and Fido, run on a level frictionless surface. Rover runs eastward with a momentum of 24 kg . m/s, and Fido runs northward with momentum 10 kg . m/s. They make a sudden perfectly inelastic collision. What is the magnitude of their combined momentum after the collision?
A)14 kg . m/s
B)26 kg . m/s
C)34 kg . m/s
D)It cannot be determined without knowing the masses and velocities of the dogs.

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Multiple Choice

Q 89Q 89

A ballerina spins initially at 1.5 rev/s when her arms are extended. She then draws in her arms to her body and her moment of inertia becomes 0.88 kg ∙ m

^{2}, and her angular speed increases to 4.0 rev/s. What was her initial moment of inertia?Free

Essay

Q 90Q 90

In a certain cyclotron, a proton of mass 1.67 × 10

^{-27}kg moves in a circle of diameter 1.6 m with an angular speed of 2.0 × 10^{6}rad/s. What is the angular momentum of the proton? A)1.3 × 10^{-21}kg ∙ m^{2}/s B)1.8 × 10^{-21}kg ∙ m^{2}/s C)2.1 × 10^{-21}kg ∙ m^{2}/s D)3.2 × 10^{-21}kg ∙ m^{2}/sFree

Multiple Choice

Q 91Q 91

Three solid, uniform, cylindrical flywheels, each of mass 65.0 kg and radius 1.47 m, rotate independently around a common axis through their centers. Two of the flywheels rotate in one direction at 8.94 rad/s, but the other one rotates in the opposite direction at 3.42 rad/s. Calculate the magnitude of the net angular momentum of the system.
A)1020 kg ∙ m

^{2}/s B)1500 kg ∙ m^{2}/s C)975 kg ∙ m^{2}/s D)940 kg ∙ m^{2}/sFree

Multiple Choice

Q 92Q 92

A uniform, solid, cylindrical flywheel of radius 1.4 m and mass 15 kg rotates at What is the magnitude of the flywheel's angular momentum?
A)40 kg ∙ m

^{2}/s B)20 kg ∙ m^{2}/s C)80 kg ∙ m^{2}/s D)60 kg ∙ m^{2}/sFree

Multiple Choice

Q 93Q 93

A uniform 135-g meter stick rotates about an axis perpendicular to the stick passing through its center with an angular speed of 3.50 rad/s. What is the magnitude of the angular momentum of the stick?
A)0.0394 kg ∙ m

^{2}/s B)0.473 kg ∙ m^{2}/s C)0.0739 kg ∙ m^{2}/s D)0.158 kg ∙ m^{2}/s E)0.0236 kg ∙ m^{2}/sFree

Multiple Choice

Q 94Q 94

An ice skater has a moment of inertia of 5.0 kg ∙ m

^{2}when her arms are outstretched, and at this time she is spinning at 3.0 rev/s. If she pulls in her arms and decreases her moment of inertia to 2.0 kg ∙ m^{2}, how fast will she be spinning? A)2.0 rev/s B)3.3 rev/s C)7.5 rev/s D)10 rev/sFree

Multiple Choice

Q 95Q 95

A figure skater rotating at 5.00 rad/s with arms extended has a moment of inertia of 2.25 kg ∙ m

^{2}. If he pulls in his arms so his moment of inertia decreases to 1.80 kg ∙ m^{2}, what will be his new angular speed? A)2.25 rad/s B)4.60 rad/s C)6.25 rad/s D)0.81 rad/sFree

Multiple Choice

Q 96Q 96

A solid wood door, 90.0 cm wide by 2.00 m tall has a mass of 35.0 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20.0 m/s and hits the door 60.0 cm from the hinged side. The ball rebounds with a speed of 16.0 m/s along the same line. What is the angular speed of the door just after the collision with the ball?
A)0.127 rad/s
B)0.925 rad/s
C)1.14 rad/s
D)2.28 rad/s
E)4.57 rad/s

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Multiple Choice

Q 97Q 97

A light-weight potter's wheel, having a moment of inertia of is spinning freely at 40.0 rpm. The potter drops a small but dense lump of clay onto the wheel, where it sticks a distance 1.2 m from the rotational axis. If the subsequent angular speed of the wheel and clay is 32 rpm, what is the mass of the clay?
A)4.2 kg
B)2.8 kg
C)3.7 kg
D)4.6 kg

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Multiple Choice

Q 98Q 98

A 40.0-kg child running at 3.00 m/s suddenly jumps onto a stationary playground merry-go-round at a distance 1.50 m from the axis of rotation of the merry-go-round. The child is traveling tangential to the edge of the merry-go-round just before jumping on. The moment of inertia about its axis of rotation is 600 kg ∙ m

^{2}and very little friction at its rotation axis. What is the angular speed of the merry-go-round just after the child has jumped onto it? A)0.788 rad/s B)0.261 rad/s C)6.28 rev/s D)2.00 rad/s E)3.14 rev/sFree

Multiple Choice

Q 99Q 99

A 5.0-m radius playground merry-go-round with a moment of inertia of 2000 kg ∙ m

^{2}is rotating freely with an angular speed of 1.0 rad/s. Two people, each of mass 60 kg, are standing right outside the edge of the merry-go-round and suddenly step onto the edge with negligible speed relative to the ground. What is the angular speed of the merry-go-round right after the two people have stepped on? A)0.20 rad/s B)0.40 rad/s C)0.60 rad/s D)0.80 rad/s E)0.67 rad/sFree

Multiple Choice

Q 100Q 100

A 24.5-kg child is standing on the outer edge of a horizontal merry-go-round that has a moment of inertia of about a vertical axis through its center and a radius of 2.40 m. The entire system (including the child)is initially rotating at 0.180 rev/s. Find the angular velocity if the child moves to a new position 1.10 m from the center of the merry-go-round.

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Essay

Q 101Q 101

Initially, a small 2.0-kg rock is whirling at the end of a very thin string in a circular path of radius 0.75 m on a horizontal frictionless surface, as shown in the figure. The initial tangential speed of the rock was 5.0 m/s. The string has been slowly winding around a vertical rod, and a few seconds later the length of the string has shortened to 0.25 m. What is the instantaneous speed of the mass at the moment the string reaches a length of 0.25 m?
A)3.9 m/s
B)9.3 m/s
C)15 m/s
D)225 m/s
E)75 m/s

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Multiple Choice

Q 102Q 102

A solid, uniform, horizontal disk with a diameter of 2.0 m and a mass of 4.0 kg freely rotates at 36 rpm about a vertical axis through its center. A small 0.50-kg stone is suddenly dropped onto the disk and sticks to the disk at a distance of 80 cm from the axis of rotation. The figure shows before and after views.
(a)Before the stone fell, what was the moment of inertia of the disk about its central axis?
(b)After the stone stuck, what was the moment of inertia of the system about the same axis?
(c)What is the angular velocity of the disk (in rpm)after the stone fell onto the disk?

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Q 103Q 103

A puck moves on a horizontal air table. It is attached to a string that passes through a hole in the center of the table. As the puck rotates about the hole, the string is pulled downward very slowly and shortens the radius of rotation, so the puck gradually spirals in towards the center. By what factor will the puck's angular speed have changed when the string's length has decreased to one-half of its original length?
A)2
B)4
C)
D)1
E)1/2

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Multiple Choice