# Quiz 10: Energy and Work

Physics & Astronomy

Q 1Q 1

Person X pushes twice as hard against a stationary brick wall as person Y. Which one of the following statements is correct?
A)Both do positive work, but person X does four times the work of person Y.
B)Both do positive work, but person X does twice the work of person Y.
C)Both do the same amount of positive work.
D)Both do zero work.
E)Both do positive work, but person X does one-half the work of person Y.

Free

Multiple Choice

D

Q 2Q 2

Two men, Joel and Jerry, push against a car that has stalled, trying unsuccessfully to get it moving. Jerry stops after 10 min, while Joel is able to push for 5.0 min longer. Compare the work they do on the car.
A)Joel does 75% more work than Jerry.
B)Joel does 50% more work than Jerry.
C)Jerry does 50% more work than Joel.
D)Joel does 25% more work than Jerry.
E)Neither of them does any work.

Free

Multiple Choice

E

Q 3Q 3

If the force on an object is in the negative direction, the work it does on the object must be
A)negative.
B)positive.
C)The work could be either positive or negative, depending on the direction the object moves.

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Multiple Choice

C

Q 4Q 4

A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process?
A)180 J
B)90 J
C)45 J
D)0 J
E)900 J

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Multiple Choice

Q 5Q 5

You throw a baseball straight up. Compare the sign of the work done by gravity while the ball goes up with the sign of the work done by gravity while it goes down.
A)The work is positive on the way up and positive on the way down.
B)The work is positive on the way up and negative on the way down.
C)The work is negative on the way up and positive on the way down.
D)The work is negative on the way up and on the way down because gravity is always downward.

Free

Multiple Choice

Q 6Q 6

Which one has larger kinetic energy: a 500-kg object moving at 40 m/s or a 1000-kg object moving at 20 m/s?
A)The 500-kg object
B)The 1000-kg object
C)Both have the same kinetic energy.

Free

Multiple Choice

Q 7Q 7

A truck has four times the mass of a car and is moving with twice the speed of the car. If K

_{t}and K_{c}refer to the kinetic energies of truck and car respectively, it is correct to say that A)K_{t}= 16K_{c}. B)K_{t}= 4K_{c}. C)K_{t}= 2K_{c}. D)K_{t}= K_{c}. E)K_{t}= Kc.Free

Multiple Choice

Q 8Q 8

Three cars (car F, car G, and car H)are moving with the same speed and slam on their brakes. The most massive car is car F, and the least massive is car H. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, which car travels the longest distance to skid to a stop?
A)They all travel the same distance in stopping.
B)Car F
C)Car G
D)Car H

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Multiple Choice

Q 9Q 9

Three cars (car L, car M, and car N)are moving with the same speed and slam on their brakes. The most massive car is car L, and the least massive is car N. If the tires of all three cars have identical coefficients of kinetic friction with the road surface, for which car is the amount of work done by friction in stopping it the greatest?
A)The amount of work done by friction is the same for all cars.
B)Car L
C)Car M
D)Car N

Free

Multiple Choice

Q 10Q 10

A 4.0 kg object is moving with speed 2.0 m/s. A 1.0 kg object is moving with speed 4.0 m/s. Both objects encounter the same constant braking force, and are brought to rest. Which object travels the greater distance before stopping?
A)the 4.0 kg object
B)the 1.0 kg object
C)Both objects travel the same distance.
D)It cannot be determined from the information given.

Free

Multiple Choice

Q 11Q 11

You slam on the brakes of your car in a panic, and skid a certain distance on a straight level road. If you had been traveling twice as fast, what distance would the car have skidded, under the same conditions?
A)It would have skidded 4 times farther.
B)It would have skidded twice as far.
C)It would have skidded 1.4 times farther.
D)It would have skidded one half as far.
E)It is impossible to tell from the information given.

Free

Multiple Choice

Q 12Q 12

Which requires more work, increasing a car's speed from 0 mph to 30 mph or from 50 mph to 60 mph?
A)0 mph to 30 mph
B)50 mph to 60 mph
C)It is the same in both cases.

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Multiple Choice

Q 13Q 13

A stone is held at a height h above the ground. A second stone with four times the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is
A)one-fourth as much.
B)one-half as much.
C)twice as much.
D)four times as much.
E)the same.

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Multiple Choice

Q 14Q 14

You and your friend, who weighs the same as you, want to go to the top of the Eiffel Tower. Your friend takes the elevator straight up. You decide to walk up the spiral stairway, taking longer to do so. Compare the gravitational potential energy of you and your friend, after you both reach the top.
A)It is impossible to tell, since the times you both took are unknown.
B)It is impossible to tell, since the distances you both traveled are unknown.
C)Your friend's gravitational potential energy is greater than yours, because he got to the top faster.
D)Both of you have the same amount of gravitational potential energy at the top.
E)Your gravitational potential energy is greater than that of your friend, because you traveled a greater distance in getting to the top.

Free

Multiple Choice

Q 15Q 15

The graphs shown show the magnitude F of the force exerted by a spring as a function of the distance x the spring has been stretched. For which one of the graphs does the spring obey Hooke's law?
A)Graph a
B)Graph b
C)Graph c
D)Graph d
E)Graph e

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Multiple Choice

Q 16Q 16

A heavy dart and a light dart are launched horizontally on a frictionless table by identical ideal springs. Both springs were initially compressed by the same amount. Which of the following statements about these darts are correct? (There could be more than one correct choice.)
A)The darts both have the same kinetic energy just as they move free of the spring.
B)The lighter dart leaves the spring moving faster than the heavy dart.
C)The heavy dart had more initial elastic potential energy than the light dart.
D)Both darts move free of the spring with the same speed.
E)Both darts had the same initial elastic potential energy.

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Multiple Choice

Q 17Q 17

When you throw a pebble straight up with initial speed V, it reaches a maximum height H with no air resistance. At what speed should you throw it up vertically so it will go twice as high?
A)16V
B)8V
C)4V
D)2V
E) V

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Multiple Choice

Q 18Q 18

When you drop a pebble from height H, it reaches the ground with speed V if there is no air resistance. From what height should you drop it so it will reach the ground with twice speed?
A) H
B)2H
C)4H
D)8H
E)16H

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Multiple Choice

Q 19Q 19

When you drop a pebble from height H, it reaches the ground with kinetic energy K if there is no air resistance. From what height should you drop it so it will reach the ground with twice as much kinetic energy?
A) H
B)2H
C)4H
D)8H
E)16H

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Multiple Choice

Q 20Q 20

Two objects, one of mass m and the other of mass 2m, are dropped from the top of a building. If there is no air resistance, when they hit the ground
A)both will have the same kinetic energy.
B)the heavier one will have twice the kinetic energy of the lighter one.
C)the heavier one will have four times the kinetic energy of the lighter one.
D)the heavier one will have half the kinetic energy of the lighter one.
E)the heavier one will have one-fourth the kinetic energy of the lighter one.

Free

Multiple Choice

Q 21Q 21

Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first and then leveling out. How does the speed v

_{1}of a swimmer reaching the bottom of slide 1 compare with v_{2}, the speed of a swimmer reaching the end of slide 2? A)v_{1}> v_{2}B)v_{1}< v_{2}C)v_{1}= v_{2}D)The heavier swimmer will have a greater speed than the lighter swimmer, no matter which slide he uses. E)No simple relationship exists between v_{1}and v_{2}.Free

Multiple Choice

Q 22Q 22

Two frisky otters slide down frictionless hillsides of the same height but different slopes. The slope of the hill of otter 1 is 30°, while the slope of the hill of otter 2 is 60°. If both start from rest, which otter is moving faster when she reaches the bottom of her hill?
A)Otter 1 is moving faster.
B)Otter 2 is moving faster.
C)The heavier otter is moving faster, no matter which hill she used.
D)Both otters have the same speed at the bottom.
E)The otter that took the shorter time is moving faster.

Free

Multiple Choice

Q 23Q 23

A lightweight object and a very heavy object are sliding with equal speeds along a level frictionless surface. They both slide up the same frictionless hill with no air resistance. Which object rises to a greater height?
A)The heavy object, because it has greater initial kinetic energy.
B)The light object, because gravity slows it down less.
C)The lightweight object, because the force of gravity on it is less.
D)The heavy object, because it has more mass to carry it up the hill.
E)They both slide to exactly the same height.

Free

Multiple Choice

Q 24Q 24

A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock X is thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. If the ground at the base of the cliff is level, which rock hits the ground with the greatest speed if there is no air resistance?
A)Rock X
B)Rock Y
C)Rock Z
D)They all hit the ground with the same speed.

Free

Multiple Choice

Q 25Q 25

Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed twice as high as Bill. If there is no air resistance, the maximum height of Joe's ball will be
A)four times that of Bill's ball.
B)two times that of Bill's ball.
C)equal to that of Bill's ball.
D)eight times that of Bill's ball.
E)roughly 1.4 times that of Bill's ball.

Free

Multiple Choice

Q 26Q 26

A stone can slide down one of four different frictionless ramps, as shown in the figure. For which ramp will the speed of the ball be the greatest at the bottom?
A)Ramp X
B)Ramp Y
C)Ramp Z
D)The speed of the ball will be the same for all ramps.

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Multiple Choice

Q 27Q 27

A girl throws a stone from a bridge. Consider the following ways she might throw the stone. The speed of the stone as it leaves her hand is the same in each case. Case A: Thrown straight up.
Case B: Thrown straight down.
Case C: Thrown out at an angle of 45° above horizontal.
Case D: Thrown straight out horizontally.
In which case will the speed of the stone be greatest when it hits the water below if there is no significant air resistance?
A)Case A
B)Case B
C)Case C
D)Case D
E)The speed will be the same in all cases.

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Multiple Choice

Q 28Q 28

Two identical grasshoppers jump into the air with the same initial speed and experience no air resistance. Grasshopper A goes straight up, but grasshopper B goes up at a 66° angle above the horizontal. Which of the following statements about these grasshoppers are correct? (There could be more than one correct choice.)
A)At their highest point, both of them have the same amount of gravitational potential energy.
B)At their highest point, both of them have the same amount of kinetic energy.
C)At their highest point, both of them have the same amount of mechanical energy.
D)At their highest point, grasshopper B is moving faster than grasshopper A.
E)At their highest point, grasshopper A has more gravitational potential energy than grasshopper B.

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Multiple Choice

Q 29Q 29

A heavy rock and a light rock are dropped from the same height and experience no significant air resistance as they fall. Which of the following statements about these rocks are correct? (There could be more than one correct choice.)
A)Both rocks have the same kinetic energy when they reach the ground.
B)Both rocks have the same speed when they reach the ground.
C)The heavier rock reaches the ground before the lighter rock.
D)Just as they were released, both rocks had the same amount of gravitational potential energy.
E)When they reach the ground, the heavier rock has more kinetic energy than the lighter rock.

Free

Multiple Choice

Q 30Q 30

A heavy stone and a light stone are released from rest in such away that they both have the same amount of gravitational potential energy just as they are released. Air resistance is negligibly small. Which of the following statements about these stones are correct? (There could be more than one correct choice.)
A)The initial height of the light stone is greater than the initial height of the heavy stone.
B)The stones must have been released from the same height.
C)The stones both have the same speed just as they reach the ground.
D)Just as it reaches the ground, the light stone is traveling faster than the heavy stone.
E)The stones both have the same kinetic energy just as they reach the ground.

Free

Multiple Choice

Q 31Q 31

A 1-kg ball is released from a height of 6 m, and a 2-kg ball is released from a height of 3 m. Air resistance is negligible as they fall. Which of the following statements about these balls are correct? (There could be more than one correct choice.)
A)As they reach the ground, the 1-kg ball will have more kinetic energy than the 2-kg ball because it was dropped from a greater height.
B)As they reach the ground, the 1-kg ball will be moving faster than the 2-kg ball.
C)Both balls will reach the ground with the same speed.
D)Both balls will reach the ground with the same kinetic energy.
E)Both balls will take the same time to reach the ground.

Free

Multiple Choice

Q 32Q 32

A heavy dart and a light dart are launched vertically by identical ideal springs. Both springs were initially compressed by the same amount. There is no significant air resistance. Which of the following statements about these darts are correct? (There could be more than one correct choice.)
A)The heavy dart goes higher than the light dart.
B)The light dart goes higher than the heavy dart.
C)Both darts reach the same maximum height.
D)At the maximum height, both darts have the same gravitational potential energy.
E)Both darts began moving upward with the same initial speed.

Free

Multiple Choice

Q 33Q 33

A heavy sled and a light sled, both moving horizontally with the same speed, suddenly slide onto a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction between the sleds and the rough snow is the same for both of them. Which of the following statements about these sleds are correct? (There could be more than one correct choice.)
A)Both sleds will slide the same distance on the rough snow before stopping.
B)The heavy sled will slide farther on the rough snow than the light sled.
C)The light sled will slide farther on the rough snow than the heavy sled.
D)The friction from the snow will do more negative work on the heavy sled than on the light sled.
E)The friction from the snow will do the same amount of work on both sleds.

Free

Multiple Choice

Q 34Q 34

A heavy sled and a light sled, both moving horizontally with the same kinetic energy, suddenly slide onto a rough patch of snow and eventually come to a stop. The coefficient of kinetic friction between the sleds and the rough snow is the same for both of them. Which of the following statements about these sleds are correct? (There could be more than one correct choice.)
A)Both sleds will slide the same distance on the rough snow before stopping.
B)The heavy sled will slide farther on the rough snow than the light sled.
C)The light sled will slide farther on the rough snow than the heavy sled.
D)On the rough snow, the change in kinetic energy will be the same for both sleds.
E)The friction from the snow will do the same amount of work on both sleds.

Free

Multiple Choice

Q 35Q 35

If a stone is dropped with an initial gravitational potential energy of 100 J but reaches the ground with a kinetic energy of only 75 J, this is a violation of the principle of conservation of energy.

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True False

Q 36Q 36

If the units of your answer are kg ∙ m

^{2}/s^{3}, which of the following types of quantities could your answer be? (There could be more than one correct choice.) A)kinetic energy B)potential energy C)force D)power E)workFree

Multiple Choice

Q 37Q 37

Two cyclists who weigh the same and have identical bicycles ride up the same mountain, both starting at the same time. Joe rides straight up the mountain, and Bob rides up the longer road that has a lower grade. Joe gets to the top before Bob. Ignoring friction and wind resistance, which one of the following statements is true?
A)The amount of work done by Joe is equal to the amount of work done by Bob, but the average power exerted by Joe is greater than that of Bob.
B)The amount of work done by Joe is greater than the amount of work done by Bob, and the average power exerted by Joe is greater than that of Bob.
C)Bob and Joe exerted the same amount of work, and the average power of each cyclist was also the same.
D)The average power exerted by Bob and Joe was the same, but Joe exerted more work in getting there.

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Multiple Choice

Q 38Q 38

Jill does twice as much work as Jack does and in half the time. Jill's power output is
A)the same as Jack's power output.
B)one-fourth as much as Jack's power output.
C)one-half as much as Jack's power output.
D)twice Jack's power output.
E)four times Jack's power output.

Free

Multiple Choice

Q 39Q 39

A force produces power P by doing work W in a time T. What power will be produced by a force that does six times as much work in half as much time?
A)12P
B)6P
C)P
D) P
E) P

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Multiple Choice

Q 40Q 40

In a game of pool, the white cue ball hits the #5 ball and stops, while the #5 ball moves away with the same velocity as the cue ball had originally. Both balls have the same mass. This type of collision is
A)somewhat inelastic.
B)elastic.
C)completely inelastic.

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Multiple Choice

Q 41Q 41

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is
A)perfectly elastic.
B)partially inelastic.
C)completely inelastic.
D)characterized by an increase in kinetic energy.
E)not possible because momentum is not conserved.

Free

Multiple Choice

Q 42Q 42

In the figure showing an isolated system, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is
A)perfectly elastic.
B)partially inelastic.
C)completely inelastic.
D)characterized by an increase in kinetic energy.
E)not possible because momentum is not conserved.

Free

Multiple Choice

Q 43Q 43

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after, are shown. The collision is
A)perfectly elastic.
B)partially inelastic.
C)completely inelastic.
D)characterized by an increase in kinetic energy.
E)not possible because momentum is not conserved.

Free

Multiple Choice

Q 44Q 44

An egg falls from a bird's nest in a tree and feels no effects due to the air. As it falls,
A)only its kinetic energy is conserved.
B)only its momentum is conserved.
C)both its kinetic energy and its momentum are conserved.
D)only its mechanical energy is conserved.
E)both its mechanical energy and its momentum are conserved.

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Multiple Choice

Q 45Q 45

If a quantity you calculated had units of kg ∙ m/s, what type of quantity could it be? (There could be more than one correct choice.)
A)momentum
B)kinetic energy
C)work
D)impulse
E)force

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Multiple Choice

Q 46Q 46

A railroad car collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system
A)is the same as before.
B)is half as much as before.
C)is one third as much as before.
D)is one fourth as much as before.
E)is one quarter as much as before.

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Multiple Choice

Q 47Q 47

A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. As a result of this bounce, which of the following quantities of the ball are conserved? (There could be more than one correct choice.)
A)the kinetic energy of the ball
B)the momentum of the ball
C)both the momentum and the kinetic energy of the ball
D)None of the above quantities are conserved.

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Multiple Choice

Q 48Q 48

On a horizontal frictionless air table, a puck runs into an ideal horizontal spring that is fastened to the table. The puck compresses the spring by 15 cm before coming to rest. During the compression process, which quantities are conserved?
A)only the momentum of the puck
B)only the kinetic energy of the puck
C)only the mechanical energy (kinetic plus potential)of the puck
D)the momentum and the mechanical energy of the puck
E)the momentum and the kinetic energy of the puck

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Multiple Choice

Q 49Q 49

Two objects of different mass have equal, non-zero kinetic energies. Which object has the greater magnitude momentum?
A)the heavier object
B)the lighter object
C)They both have the same magnitude momentum.

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Multiple Choice

Q 50Q 50

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?
A)the heavier object
B)the lighter object
C)They both have the same kinetic energy.

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Multiple Choice

Q 51Q 51

If you want to double the kinetic energy of a gas molecule, by what factor must you increase its momentum?
A)
B)2
C)2
D)4
E)16

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Multiple Choice

Q 52Q 52

If you want to double the momentum of a gas molecule, by what factor must you increase its kinetic energy?
A)
B)2
C)2
D)4
E)16

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Multiple Choice

Q 53Q 53

A firecracker explodes in midair and breaks up into many fragments. Which of the following statements are true regarding conditions immediately before and immediately after the explosion: I. The total momentum of the fragments is equal to the original momentum of the firecracker.
II. The total kinetic energy of the fragments is equal to the original kinetic energy of the firecracker.
A)Statement I only
B)Statement II only
C)Both Statement I and Statement II
D)Neither statement is true.

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Multiple Choice

Q 54Q 54

Consider a uniform hoop of radius R and mass M rolling without slipping. Which is larger, its translational kinetic energy or its rotational kinetic energy?
A)Translational kinetic energy is larger.
B)Rotational kinetic energy is larger.
C)Both are equal.
D)You need to know the speed of the hoop to tell.

Free

Multiple Choice

Q 55Q 55

Consider a solid uniform sphere of radius R and mass M rolling without slipping. Which form of its kinetic energy is larger, translational or rotational?
A)Translational kinetic energy is larger.
B)Rotational kinetic energy is larger.
C)Both are equal.
D)You need to know the speed of the sphere to tell.

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Multiple Choice

Q 56Q 56

A solid sphere and a solid cylinder, both uniform and of the same mass and radius, roll without slipping at the same forward speed. It is correct to say that the total kinetic energy of the solid sphere is
A)more than the total kinetic energy of the cylinder.
B)less than the total kinetic energy of the cylinder.
C)equal to the total kinetic energy of the cylinder.

Free

Multiple Choice

Q 57Q 57

A disk and a hoop of the same mass and radius are released at the same time at the top of an inclined plane. If both are uniform, which one reaches the bottom of the incline first if there is no slipping?
A)The hoop
B)The disk
C)Both reach the bottom at the same time.

Free

Multiple Choice

Q 58Q 58

A solid sphere, solid cylinder, and a hollow pipe all have equal masses and radii. If the three of them are released simultaneously at the top of an inclined plane and do not slip, which one will reach the bottom first?
A)sphere
B)pipe
C)cylinder
D)The pipe and cylinder arrive together before the sphere.
E)They all reach the bottom at the same time.

Free

Multiple Choice

Q 59Q 59

A disk, a hoop, and a solid sphere are released at the same time at the top of an inclined plane. They are all uniform and roll without slipping. In what order do they reach the bottom?
A)disk, hoop, sphere
B)hoop, sphere, disk
C)sphere, disk, hoop
D)hoop, disk, sphere

Free

Multiple Choice

Q 60Q 60

A small uniform disk and a small uniform sphere are released simultaneously at the top of a high inclined plane, and they roll down without slipping. Which one will reach the bottom first?
A)the one of smallest diameter
B)the one of greatest mass
C)the disk
D)the sphere
E)They will reach the bottom at the same time.

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Multiple Choice

Q 61Q 61

Suppose a uniform solid sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The linear velocity of the sphere at the bottom of the incline depends on
A)the mass of the sphere.
B)the radius of the sphere.
C)both the mass and the radius of the sphere.
D)neither the mass nor the radius of the sphere.

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Multiple Choice

Q 62Q 62

Suppose a solid uniform sphere of mass M and radius R rolls without slipping down an inclined plane starting from rest. The angular velocity of the sphere at the bottom of the incline depends on
A)the mass of the sphere.
B)the radius of the sphere.
C)both the mass and the radius of the sphere.
D)neither the mass nor the radius of the sphere.

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Multiple Choice

Q 63Q 63

A uniform ball is released from rest on a no-slip surface, as shown in the figure. After reaching its lowest point, the ball begins to rise again, this time on a frictionless surface. When the ball reaches its maximum height on the frictionless surface, it is
A)higher than when it was released.
B)lower than when it was released.
C)at the same height from which it was released.
D)It is impossible to tell without knowing the mass of the ball.
E)It is impossible to tell without knowing the radius of the ball.

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Multiple Choice

Q 64Q 64

Two uniform solid balls, one of radius R and mass M, the other of radius 2R and mass 8M, roll down a high incline. They start together from rest at the top of the incline. Which one will reach the bottom of the incline first?
A)The small sphere arrives first.
B)Both reach the bottom at the same time.
C)The large sphere arrives first.

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Multiple Choice

Q 65Q 65

A spinning ice skater on extremely smooth ice is able to control the rate at which she rotates by pulling in her arms. Which of the following statements are true about the skater during this process? (There could be more than one correct choice.)
A)Her angular momentum remains constant.
B)Her moment of inertia remains constant.
C)Her kinetic energy remains constant.
D)She is subject to a constant non-zero torque.

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Multiple Choice

Q 66Q 66

When is the angular momentum of a system constant?
A)Only when its total kinetic energy is constant.
B)Only when no net external force acts on the system.
C)Only when the linear momentum and the energy are constant.
D)Only when no net external torque acts on the system.
E)Only when the moment of inertia is constant.

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Multiple Choice

Q 67Q 67

How much work would a child do while pulling a 12-kg wagon a distance of with a force?
A)95 J
B)52 J
C)67 J
D)109 J

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Multiple Choice

Q 68Q 68

A child does 350 J of work while pulling a box from the ground up to his tree house at a steady speed with a light rope. The tree house is above the ground. What is the mass of the box?
A)8.9 kg
B)5.3 kg
C)6.7 kg
D)8.0 kg

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Multiple Choice

Q 69Q 69

You carry a 7.0-kg bag of groceries above the ground at constant speed across a room. How much work do you do on the bag in the process?
A)0.00 J
B)82 J
C)185 J
D)157 J

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Multiple Choice

Q 70Q 70

It requires 0.30 kJ of work to fully drive a stake into the ground. If the average resistive force on the stake by the ground is how long is the stake?
A)0.36 m
B)0.23 m
C)0.31 m
D)0.41 m

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Multiple Choice

Q 71Q 71

A crane lifts a 425 kg steel beam vertically upward a distance of How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s

^{2}? Neglect frictional forces. A)4.7 × 10^{5}J B)2.7 × 10^{5}J C)3.2 × 10^{5}J D)4.0 × 10^{5 J}Free

Multiple Choice

Q 72Q 72

A traveler pulls on a suitcase strap at an angle 36° above the horizontal. If of work are done by the strap while moving the suitcase a horizontal distance of what is the tension in the strap?
A)46 N
B)37 N
C)52 N
D)56 N

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Multiple Choice

Q 73Q 73

A 500-kg elevator is pulled upward with a constant force of 5500 N for a distance of 50.0 m.
(a)What is the work done by the 5500-N force?
(b)What is the work done by gravity?
(c)What is the net work done on the elevator?

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Essay

Q 74Q 74

A 30-N box is pulled upward 6.0 m along the surface of a ramp that rises at 37° above the horizontal. How much work does gravity do on the box during this process?
A)-1100 J
B)-110 J
C)-140 J
D)-180 J
E)120 J

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Multiple Choice

Q 75Q 75

Matthew pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force on the wagon of 60.0 N at an angle of 37.0° above the horizontal. If he pulls her a distance of 12.0 m, how much work does Matthew do?
A)185 J
B)433 J
C)575 J
D)720 J

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Multiple Choice

Q 76Q 76

Find the net work done by friction on a box that moves in a complete circle of radius on a uniform horizontal floor. The coefficient of kinetic friction between the floor and the box is 0.25, and the box weighs
A)190 J
B)0 J
C)1800 J
D)370 J

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Multiple Choice

Q 77Q 77

A 2.0-kg object is lifted vertically through 3.00 m by a 150-N force. How much work is done on the object by gravity during this process?

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Essay

Q 78Q 78

A person carries a 25.0-N rock through the path shown in the figure, starting at point A and ending at point B. The total time from A to B is 1.50 min. How much work did gravity do on the rock between A and B?
A)625 J
B)20.0 J
C)275 J
D)75 J
E)0 J

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Multiple Choice

Q 79Q 79

A person carries a 2.00-N pebble through the path shown in the figure, starting at point A and ending at point B. The total time from A to B is 6.75 min. How much work did gravity do on the rock between A and B?
A)30.0 J
B)-30.0 J
C)-56.0 J
D)56.0 J
E)-36.0 J

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Multiple Choice

Q 80Q 80

A stone with a mass of 1.0 kg is tied to the end of a light string which keeps it moving in a circle with a constant speed of 4.0 m/s on a perfectly smooth horizontal tabletop. The radius of the path is 0.60 m. How much work does the tension in the string do on the stone as it makes one-half of a complete circle?
A)100 J
B)3.8 J
C)0 J
D)40 J
E)80 J

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Multiple Choice

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Essay

Q 82Q 82

How much kinetic energy does a 0.30-kg stone have if it is thrown at
A)290 J
B)580 J
C)440 J
D)510 J

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Multiple Choice

Q 83Q 83

An object hits a wall and bounces back with half of its original speed. What is the ratio of the final kinetic energy to the initial kinetic energy of the object?
A)1/2
B)1/4
C)1/8
D)1/16

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Multiple Choice

Q 84Q 84

A 1000-kg car is moving at 15 km/h. If a 2000-kg truck has 23 times the kinetic energy of the car, how fast is the truck moving?
A)51 km/h
B)72 km/h
C)61 km/h
D)41 km/h

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Multiple Choice

Q 85Q 85

What is the minimum energy needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s?
A)1.10 MJ
B)10.0 kJ
C)20.0 kJ
D)40.0 kJ
E)0.960 MJ

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Multiple Choice

Q 86Q 86

A 1.0-kg object moving in a certain direction has a kinetic energy of 2.0 J. It hits a wall and comes back with half its original speed. What is the kinetic energy of this object at this point?
A)2.0 J
B)1.0 J
C)0.50 J
D)0.25 J
E)4.0 J

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Multiple Choice

Q 87Q 87

How much work must be done by frictional forces in slowing a 1000-kg car from to rest?
A)3.41 × 10

^{5}J B)2.73 × 10^{5}J C)4.09 × 10^{5}J D)4.77 × 10^{5}JFree

Multiple Choice

Q 88Q 88

When a car of mass accelerates from 10.0 m/s to some final speed, 4.00 × 10

^{5}J of work are done. Find this final speed. A)28.0 m/s B)22.4 m/s C)25.2 m/s D)30.8 m/sFree

Multiple Choice

Q 89Q 89

A 10-kg dog is runnng with a speed of 5.0 m/s. What is the minimum work required to stop the dog in 2.40 s?
A)50 J
B)75 J
C)100 J
D)125 J

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Multiple Choice

Q 90Q 90

How large a net force is required to accelerate a 1600-kg SUV from rest to a speed of 25 m/s in a distance of 200 m?
A)1600 N
B)0 N
C)200 N
D)400 N
E)2500 N

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Multiple Choice

Q 91Q 91

A 100-N force has a horizontal component of 80 N and a vertical component of 60 N. The force is applied to a cart on a level frictionless floor. The cart starts from rest and moves 2.0 m horizontally along the floor due to this force. What is the cart's final kinetic energy?
A)200 J
B)160 J
C)120 J
D)zero

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Multiple Choice

Q 92Q 92

A 1000-kg car experiences a net force of 9500 N while slowing down from 30 m/s to How far does it travel while slowing down?
A)34 m
B)31 m
C)37 m
D)41 m

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Multiple Choice

Q 93Q 93

A stone initially moving at 8.0 m/s on a level surface comes to rest due to friction after it travels 11 m. What is the coefficient of kinetic friction between the stone and the surface?
A)0.13
B)0.25
C)0.30
D)0.43
E)0.80

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Multiple Choice

Q 94Q 94

A sled having a certain initial speed on a horizontal surface comes to rest after traveling 10 m. If the coefficient of kinetic friction between the object and the surface is 0.20, what was the initial speed of the object?
A)9.8 m/s
B)6.3 m/s
C)3.6 m/s
D)7.2 m/s
E)8.9 m/s

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Multiple Choice

Q 95Q 95

On an alien planet, an object moving at 4.0 m/s on the horizontal ground comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the surface is 0.20, what is the value of g on that planet?
A)4.0 m/s

^{2}B)6.0 m/s^{2}C)8.0 m/s^{2}D)10 m/s^{2}E)12 m/s^{2}Free

Multiple Choice

Q 96Q 96

A driver, traveling at 22 m/s, slows down her 2000 kg truck to stop for a red light. What work is done on the truck by the friction force of the road?
A)-2.2 × 10

^{4}J B)-4.4 × 10^{4}J C)-4.8 × 10^{5}J D)-9.7 × 10^{5}JFree

Multiple Choice

Q 97Q 97

The kinetic friction force that a horizontal surface exerts on a 60.0-kg object is 50.0 N. If the initial speed of the object is 25.0 m/s, what distance will it slide before coming to a stop?
A)15.0 m
B)30.0 m
C)375 m
D)750 m

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Multiple Choice

Q 98Q 98

A stone is moving on a rough level surface. It has 24 J of kinetic energy, and the friction force on it is a constant 0.50 N. What is the maximum distance it can slide?
A)2.0 m
B)12 m
C)24 m
D)48 m

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Multiple Choice

Q 99Q 99

In a ballistics test, a 28-g bullet pierces a sand bag that is thick. If the initial bullet velocity was and it emerged from the sandbag moving at what was the magnitude of the friction force (assuming it to be constant)that the bullet experienced while it traveled through the bag?
A)130 N
B)38 N
C)13 N
D)1.3 N

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Multiple Choice

Q 100Q 100

A certain car traveling at 34.0 mph skids to a stop in 29 meters from the point where the brakes were applied. In approximately what distance would the car have stopped had it been going 105.4 mph?
A)279 m
B)158 m
C)90 m
D)51 m
E)29 m

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Multiple Choice

Q 101Q 101

How high a hill would a 75-kg hiker have to climb to increase her gravitational potential energy by 10,000 J?

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Essay

Q 102Q 102

You do 116 J of work while pulling your sister back on a fritctionless swing, whose chain is long, until the swing makes an angle of 32.0° with the vertical. What is your sister's mass?
A)15.3 kg
B)13.0 kg
C)17.6 kg
D)19.0 kg

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Multiple Choice

Q 103Q 103

A tennis ball bounces on the floor three times, and each time it loses 23.0% of its energy due to heating. How high does it bounce after the third time, if we released it from the floor?
A)180 cm
B)18 cm
C)180 mm
D)240 cm

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Multiple Choice

Q 104Q 104

A 10-kg mass, hung by an ideal spring, causes the spring to stretch 2.0 cm. What is the spring constant (force constant)for this spring?
A)5.0 N/cm
B)49 N/cm
C)0.20 N/cm
D)20 N/m
E)0.0020 N/cm

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Multiple Choice

Q 105Q 105

An ideal spring stretches by 21.0 cm when a 135-N object is hung from it. If instead you hang a fish from this spring, what is the weight of a fish that would stretch the spring by
A)199 N
B)91 N
C)145 N
D)279 N

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Multiple Choice

Q 106Q 106

An ideal spring has a spring constant (force constant)of 2500 N/m. is stretched 4.0 cm. How much work is required to stretch the spring by 4.0 cm?
A)4.0 J
B)0.00 J
C)1.0 J
D)3.0 J
E)2.0 J

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Multiple Choice

Q 107Q 107

You want to store 1,000 J of energy in an ideal spring when it is compressed by only 2.5 cm. What should be the force constant (spring constant)of this spring?

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Essay

Q 108Q 108

If 4.0 J of work are performed in stretching an ideal spring with a spring constant (force constant)of 2500 N/m, by what distance is the spring stretched?
A)3.2 cm
B)3.2 m
C)0.3 cm
D)5.7 m
E)5.7 cm

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Multiple Choice

Q 109Q 109

If the work done to stretch an ideal spring by 4.0 cm is 6.0 J, what is the spring constant (force constant)of this spring?
A)300 N/m
B)3000 N/m
C)3500 N/m
D)7500 N/m
E)6000 N/m

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Multiple Choice

Q 110Q 110

An ideal spring has a spring constant (force constant)of 60 N/m. How much energy does it store when it is stretched by 1.0 cm?
A)0.0030 J
B)0.30 J
C)60 J
D)600 J

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Multiple Choice

Q 111Q 111

How much work is required to stretch an ideal spring of spring constant (force constant)40 N/m from x = 0.20 m to x = 0.25 m if the unstretched position is at x = 0.00 m?
A)0.45 J
B)0.80 J
C)1.3 J
D)0.050 J

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Multiple Choice

Q 112Q 112

An ideal spring with a force constant (spring constant)of 15 N/m is initially compressed by 3.0 cm from its uncompressed position. How much work is required to compress the spring an additional 4.0 cm?
A)0.0068 J
B)0.012 J
C)0.024 J
D)0.030 J

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Multiple Choice

Q 113Q 113

It takes 87 J of work to stretch an ideal spring from 1.4 m to 2.9 m from equilibrium. What is the value of the spring constant (force constant)of this spring?
A)27 N/m
B)77 N/m
C)52 N/m
D)39 N/m

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Multiple Choice

Q 114Q 114

An ideal spring with a spring constant (force constant)of is stretched from equilibrium to 2.9 m. How much work is done in the process?
A)93 J
B)186 J
C)47 J
D)121 J

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Multiple Choice

Q 115Q 115

A rock falls from a vertical cliff that is 4.0 m tall and experiences no significant air resistance as it falls. At what speed will its gravitational potential energy (relative to the base of the cliff)be equal to its kinetic energy?
A)3.1 m/s
B)4.4 m/s
C)6.3 m/s
D)8.9 m/s
E)13 m/s

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Multiple Choice

Q 116Q 116

A block slides down a frictionless inclined ramp and experiences no significant air resistance. If the ramp angle is 17.0° above the horizontal and the length of the surface of the ramp is find the speed of the block as it reaches the bottom of the ramp, assuming it started sliding from rest at the top.
A)10.7 m/s
B)114 m/s
C)7.57 m/s
D)19.6 m/s

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Multiple Choice

Q 117Q 117

A prankster drops a water balloon from the top of a building. If the balloon is traveling at 29.1 m/s when it strikes a window ledge that is 1.5 m above the ground, how tall is the building? Neglect air resistance.
A)45 m
B)43 m
C)46 m
D)47 m

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Multiple Choice

Q 118Q 118

A spring-loaded dart gun is used to shoot a dart straight up into the air, and the dart reaches a maximum height of 24 meters. The same dart is shot up a second time from the same gun, but this time the spring is compressed only half as far (compared to the first shot). How far up does the dart go this time (neglect all friction and assume the spring is ideal)?
A)6.0 m
B)12 m
C)3.0 m
D)48 m

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Multiple Choice

Q 119Q 119

A bead is moving with a speed of 20 m/s at position A on the track shown in the figure. This track is friction-free, and there is no appreciable air resistance. What is the speed of the bead at point C?
A)0 m/s
B)34 m/s
C)69 m/s
D)20 m/s
E)We cannot solve this problem without knowing the mass of the bead.

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Multiple Choice

Q 120Q 120

A frictionless simple pendulum, with a small but dense 4.4-kg mass at the end and a length of 75 cm, is released from rest at an angle of 50° with the vertical.
(a)To what height above its lowest point does the mass swing on the other side?
(b)What is the speed of the mass at the bottom of the swing?

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Essay

Q 121Q 121

The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?
A)10 m/s
B)22 m/s
C)44 m/s
D)62 m/s
E)120 m/s

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Multiple Choice

Q 122Q 122

What is the minimum energy needed to lift a 1.0-kg rocket to a height of 200 km and to give it a speed of 8.0 km/s at that height? (Neglect air resistance and the small decrease in g over that distance.)
A)34 TJ
B)34 kJ
C)34 MJ
D)34 GJ
E)34 J

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Multiple Choice

Q 123Q 123

Assuming negligible friction, what spring constant (force constant)would be needed by the spring in a "B-B gun" to fire a 10-g pellet to a height of 100 m if the spring is initially compressed by 0.10 m?
A)20 N/cm
B)200 N/m
C)2000 N/cm
D)0.0020 N/m

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Multiple Choice

Q 124Q 124

If a spring-operated gun can shoot a pellet to a maximum height of 100 m on Earth, how high could the pellet rise if fired on the Moon, where g = 1.6 m/s

^{2}? A)17 m B)160 m C)3.6 km D)100 m E)610 mFree

Multiple Choice

Q 125Q 125

A 60-kg skier pushes off the top of a frictionless hill with an initial speed of 4.0 m/s. How fast will she be moving after dropping 10 m in elevation? Air resistance is negligible.
A)0.20 km/s
B)15 m/s
C)10 m/s
D)0.15 km/s
E)49 m/s

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Multiple Choice

Q 126Q 126

A toy rocket that weighs 10 N blasts straight up from ground level with an initial kinetic energy of 40 J. At the exact top of its trajectory, its total mechanical energy is 140 J. To what vertical height above the ground does it rise, assuming no air resistance?
A)1.0 m
B)10 m
C)14 m
D)24 m

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Multiple Choice

Q 127Q 127

A 5.0-N projectile leaves the ground with a kinetic energy of 220 J. At the highest point in its trajectory, its kinetic energy is 120 J. To what vertical height, relative to its launch point, did it rise if there was no air resistance?
A)44 m
B)24 m
C)20 m
D)10 m
E)It is impossible to determine the height without knowing the angle of launch.

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Multiple Choice

Q 128Q 128

In the figure, a ball hangs by a very light string. What is the minimum speed of the ball at the bottom of its swing (point
A)2.2 m/s
B)3.1 m/s
B)in order for it to reach point A, which is 1.0 m above the bottom of the swing?
C)4.4 m/s
D)4.9 m/s

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Multiple Choice

Q 129Q 129

A 1500-kg car moving at 25 m/s hits an initially uncompressed horizontal ideal spring with spring constant (force constant)of 2.0 × 10

^{6}N/m. What is the maximum distance the spring compresses? A)0.17 m B)0.34 m C)0.51 m D)0.68 mFree

Multiple Choice

Q 130Q 130

A small but dense 2.0-kg stone is attached to one end of a very light rod that is 1.2 m long. The other end of the rod is attached to a frictionless pivot. The rod is raised until it is vertical, with the stone above the pivot. The rod is released and the stone moves in a vertical circle with no air resistance. What is the tension in the rod as the stone moves through the bottom of the circle?
A)20 N
B)40 N
C)60 N
D)80 N
E)100 N

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Multiple Choice

Q 131Q 131

In a museum exhibit of a simple pendulum, a very small but dense 6.0-kg ball swings from a very light 2.5-m wire. The ball is released from rest when the pendulum wire makes a 65° angle with the vertical, and it swings in a circular arc with no appreciable friction or air resistance. What is the tension in the wire just as the ball swings through its lowest position?
A)11 N
B)59 N
C)68 N
D)130 N
E)0 N

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Multiple Choice

Q 132Q 132

A roller coaster starting from rest descends 35 meters in its initial drop and then rises 23 meters when it goes over the first hill, which has a circular shape over the top. If a passenger at the top of the hill feels an apparent weight equal to one-half of her normal weight, what is the radius of curvature of the first hill? Neglect any frictional losses.

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Essay

Q 133Q 133

A roller coaster starts from rest at a height h at the left side of a loop-the-loop, as shown in the figure. It is not attached to the track in anyway, and there is no friction from the track or from air resistance. If the radius of the loop is R = 6.0 m, what is the minimum height h for which the roller coaster will not fall off the track at the top of the loop?
A)21 m
B)18 m
C)15 m
D)12 m
E)8.5 m

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Multiple Choice

Q 134Q 134

A stone is released from rest at a height h at the left side of a loop-the-loop, as shown in the figure. There is no appreciable friction from the track or from air resistance. If the radius of the loop is R, what is the minimum height h for which the stone will not fall off the track at the top of the loop?
A)3.5 R
B)2.5 R
C)2.0 R
D) R
E)3.0 R

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Multiple Choice

Q 135Q 135

A small 1.4-N stone slides down a frictionless bowl, starting from rest at the rim. The bowl itself is a hemisphere of radius 75 cm. Just as the stone reaches the bottom of the bowl, how hard is the bowl pushing on it?
A)0.70 N
B)1.4 N
C)2.8 N
D)4.2 N
E)5.6 N

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Multiple Choice

Q 136Q 136

A 30-N stone is dropped from a height of 10 m and strikes the ground with a speed of 13 m/s. What average force of air friction acted on the stone as it fell?
A)4.1 N
B)2.9 N
C)0.13 kN
D)7.2 N
E)1.2 N

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Multiple Choice

Q 137Q 137

A 60-kg skier starts from rest from the top of a 50-m high slope. If the work done by friction is -6.0 kJ, what is the speed of the skier on reaching the bottom of the slope?
A)17 m/s
B)24 m/s
C)28 m/s
D)31 m/s

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Multiple Choice

Q 138Q 138

A 7.5-kg otter slides down a hill, starting from rest at the top. The sloping surface of the hill is 8.8 m long, and the top is 6.5 m above the base. If the speed of the otter at the bottom of the hill is 9.2 m/s, how much energy was lost to nonconservative forces on the hill?

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Essay

Q 139Q 139

An object with a mass of 10 kg is initially at rest at the top of a frictionless inclined plane that rises at 30° above the horizontal. At the top, the object is initially 8.0 m from the bottom of the incline, as shown in the figure. When the object is released from this position, it eventually stops at a distance d from the bottom of the inclined plane along a horizontal surface, as shown. The coefficient of kinetic friction between the horizontal surface and the object is 0.20, and air resistance is negligible. Find the distance d.
A)5.0 m
B)10 m
C)15 m
D)20 m
E)25 m

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Multiple Choice

Q 140Q 140

On a planet where g = 10.0 m/s

^{2}and air resistance is negligible, a sled is at rest on a rough inclined hill rising at 30° as shown in the figure. The object is allowed to move and it stops on a rough horizontal surface, at a distance of 4.0 m from the bottom of the hill. The coefficient of kinetic friction on the hill is 0.40. What is the coefficient of kinetic friction between the horizontal surface and the sled? A)0.10 B)0.20 C)0.31 D)0.40 E)0.60Free

Multiple Choice

Q 141Q 141

A 0.12-kg block is held in place against the spring by a 35-N horizontal external force. The external force is removed, and the block is projected with a velocity when it separates from the spring, as shown in the figure. The block descends a ramp and has a velocity at the bottom of the ramp. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.26. The block moves on to D, where it stops. By how many centimeters was the spring initially compressed?
A)0.49 cm
B)0.26 cm
C)0.18 cm
D)0.99 cm
E)0.67 cm

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Multiple Choice

Q 142Q 142

As shown in the figure, a 1.45-kg block is held in place against the spring by a 21-N horizontal external force. The external force is removed, and the block is projected with a velocity as it separates from the spring. The block descends a ramp and has a velocity at the bottom. The track is frictionless between points A and B. The block enters a rough section at B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.29. The velocity of the block is at C. The block moves on to D, where it stops. How much work is done by friction between points B and C?
A)-1.8 J
B)-3.6 J
C)-14 J
D)-6.4 J
E)-7.0 J

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Multiple Choice

Q 143Q 143

A 0.46-kg block is held in place against the spring by a 30-N horizontal external force. The external force is removed, and the block is projected with a velocity upon separation from the spring, as shown in the figure. The block descends a ramp and has a velocity at the bottom. The track is frictionless between points A and B. The block enters a rough section at point B, extending to E. The coefficient of kinetic friction between the block and the rough surface is 0.38. The velocity of the block is at point C. The block moves on to D, where it stops. What distance does the block travel between points B and D?
A)0.30 m
B)0.039 m
C)0.26 m
D)0.40 m
E)0.60 m

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Multiple Choice

Q 144Q 144

A sled is moving along a horizontal surface with a speed of 5.7 m/s. It then slides up a rough hill having a slope of 11° above the horizontal. The coefficient of kinetic friction between the sled and the surface of the hill is 0.26. How far along the surface does the block travel up the incline?

Free

Essay

Q 145Q 145

The figure shows two crates, each of mass m = 24 kg, that are connected by a very light wire. The coefficient of kinetic friction between the crate on the inclined surface and the surface itself is 0.31. Find the speed of the crates after they have moved 1.6 m starting from rest.

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Essay

Q 146Q 146

As shown in the figure, a 4.0-kg block is moving at 5.0 m/s along a horizontal frictionless surface toward an ideal spring that is attached to a wall. After the block collides with the spring, the spring is compressed a maximum distance of 0.68 m. What is the speed of the block when the spring is compressed to only one-half of the maximum distance?

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Essay

Q 147Q 147

How many joules of energy are used by a 2.0 hp motor that runs for 1.0 hour? (1 hp = 746 W)

Free

Essay

Q 148Q 148

A child pulls on a wagon with a force of If the wagon moves a total of in what is the average power delivered by the child?
A)17 W
B)21 W
C)22 W
D)26 W

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Multiple Choice

Q 149Q 149

How many joules of energy are used by a 1.0-hp motor that runs for 1.0 hour? (1 hp = 746 W)
A)3.6 kJ
B)2.7 MJ
C)45 kJ
D)4.8 J

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Multiple Choice

Q 150Q 150

A 1500-kg car accelerates from rest to 25 m/s in 7.0 s. What is the average power delivered by the engine? (1 hp = 746 W)
A)60 hp
B)70 hp
C)80 hp
D)90 hp

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Multiple Choice

Q 151Q 151

At what minimum rate is a 60.0-kg boy using energy when, in 8.00 s, he runs up a flight of stairs that is 10.0-m high?
A)75.0 W
B)735 W
C)4.80 kW
D)48.0 W

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Multiple Choice

Q 152Q 152

If electricity costs 7.06¢/kW∙h, how much would it cost you to run a stereo system per day for
A)$0.95
B)$0.14
C)$1.62
D)$2.66

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Multiple Choice

Q 153Q 153

A 1321-kg car climbs a 5.0° slope at a constant speed of Assuming that air resistance may be neglected, at what rate (in kW)must the engine deliver energy to the drive wheels of the car?
A)25 kW
B)287 kW
C)38 kW
D)48 kW

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Multiple Choice

Q 154Q 154

A typical incandescent light bulb consumes 75 W of power and has a mass of 30 g. You want to save electrical energy by dropping the bulb from a height great enough so that the kinetic energy of the bulb when it reaches the floor will be the same as the energy it took to keep the bulb on for 1.0 hour. From what height should you drop the bulb, assuming no air resistance and constant g?

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Essay

Q 155Q 155

What is the net power needed to change the speed of a 1600-kg sport utility vehicle from 15.0 m/s to 40.0 m/s in 4.00 seconds?
A)100 kW
B)10.0 kW
C)140 kW
D)14.0 kW
E)275 kW

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Multiple Choice

Q 156Q 156

Water flows over a waterfall that is 20 m high at the rate of 4.0 × 10

^{4}kg/s. If this water powers an electric generator with a 40% efficiency, how many watts of electric power can be supplied?Free

Essay

Q 157Q 157

A certain battery charger uses 12 W of power. At 6.0 cents per kilowatt-hour, how much does it cost to charge batteries for a full day?
A)28¢
B)1.4¢
C)75¢
D)1.7¢
E)2.3¢

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Multiple Choice

Q 158Q 158

A family goes on vacation for one week but forgets to turn off an electric fan that consumes electricity at the rate of 200 W. If the cost of electricity is 12.0¢/kW∙h how much does it cost (to the nearest penny)to run the fan for the week?

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Essay

Q 159Q 159

Suppose you left five 100-W light bulbs burning in the basement for two weeks. If electricity costs 10.0¢/kW∙h, (a)how much did the electricity cost (to the nearest dollar)to leave those bulbs on, and (b)how many joules of electrical energy did they consume?

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Essay

Q 160Q 160

Rita raises a 10kg package to a height of 2.5 m in 2.0 s.
(a)How much work did she do on the package?
(b)How much power was expended on the package?
(c)If she were to raise the package in 1.0 s rather than 2.0 s, how do the work and power change?

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Essay

Q 161Q 161

In a physical fitness program, a woman who weighs 510 N runs up four flights of stairs in 22 s. Each flight rises 3.1 m. (1 hp = 746 W)
(a)What is her total change in potential energy?
(b)What was the minimum average power (in watts)that she expended during the 22 s?
(c)What horsepower motor would be required to generate the same power?

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Q 162Q 162

A sand mover at a quarry lifts 2,000 kg of sand per minute a vertical distance of 12 m. The sand is initially at rest and is discharged at the top of the sand mover with speed 5.0 m/s into a loading chute. What minimum power must be supplied to this machine?
A)520 W
B)3.9 kW
C)6.7 kW
D)4.3 kW
E)1.1 kW

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Multiple Choice

Q 163Q 163

A 100%-efficient engine is being used to raise a 89-kg crate vertically upward at a steady rate. If the power output of the engine is 1620 W, how long does it take the engine to lift the crate a vertical distance of 18.7 m? Friction in the system is negligible.

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Essay

Q 164Q 164

A block of mass m = 4.4 kg, moving on frictionless surface with a speed makes a sudden perfectly elastic collision with a second block of mass M, as shown in the figure. The second block is originally at rest. Just after the collision, the 4.4-kg block recoils with a speed of What is the mass M of the second block?
A)7.7 kg
B)0 kg
C)0 kg
D)0 kg
E)0 kg

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Multiple Choice

Q 165Q 165

A block of mass m = 3.6 kg, moving on a frictionless surface with a speed makes a sudden perfectly elastic collision with a stationary block of mass M, as shown in the figure. Just after the collision, the 3.6-kg block recoils with a speed of What is the speed V of the other block?
A)6.6 m/s
B)8.0 m/s
C)9.3 m/s
D)10.7 m/s
E)12.0 m/s

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Multiple Choice

Q 166Q 166

A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g cart. What is the speed of the 270-g cart just after the collision?
A)0.678 m/s
B)0.106 m/s
C)1.36 m/s
D)1.14 m/s
E)2.72 m/s

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Multiple Choice

Q 167Q 167

A 320-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 270-g cart. What is the speed of the 320-g cart just after the collision?
A)0.68 m/s
B)0.11 m/s
C)0.21 m/s
D)1.4 m/s
E)1.1 m/s

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Multiple Choice

Q 168Q 168

A 550-g ball traveling at 8.0 m/s undergoes a sudden head-on elastic collision with a 250-g ball traveling toward it also at 8.0 m/s. What is the speed of the 250-g mass just after the collision?
A)15 m/s
B)8.0 m/s
C)4.0 m/s
D)14 m/s
E)0 m/s

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Multiple Choice

Q 169Q 169

A 340-g air track cart traveling at 1.25 m/s suddenly collides elastically with a stationary 300-g cart. What is the speed of the 300-g cart just after the collision?
A)0.0781 m/s
B)1.33 m/s
C)0.625 m/s
D)1.25 m/s
E)0.664 m/s

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Multiple Choice

Q 170Q 170

A proton of mass m is at rest when it is suddenly struck head-on by an alpha particle (which consists of 2 protons and 2 neutrons)moving at speed v. If the collision is perfectly elastic, what speed will the alpha particle have after the collision? (Assume the neutron's mass is equal to the proton's mass.)
A)zero
B)2v/3
C)3v/5
D)5v/3

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Multiple Choice

Q 171Q 171

A 50-g ball moving at 10 m/s in the +x direction suddenly collides head-on with a stationary ball of mass 100 g. If the collision is perfectly elastic, what is the velocity of each ball immediately after the collision?
A)-3.3 m/s, +6.7 m/s
B)+3.3 m/s, -6.7 m/s
C)-6.7 m/s, +3.3 m/s
D)+6.7 m/s, -3.3 m/s

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Multiple Choice

Q 172Q 172

In a perfectly elastic collision, a 400-g ball moving toward the east at 3.7 m/s suddenly collides head-on with a 200 g ball sitting at rest.
(a)Determine the velocity of the first ball just after the collision.
(b)Determine the velocity of the second ball just after the collision.
(c)Is kinetic energy conserved in this collision? How do you know?

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Q 173Q 173

A 0.140-kg baseball is dropped from rest from a height of 2.20 m above the ground and experiences negligible air resistance as it falls. It rebounds to a height of 1.60 m. What change in the ball's momentum occurs as it rebounds from the ground?
A)0.117 kg ∙ m/s upwards
B)0.117 kg ∙ m/s downwards
C)1.70 kg ∙ m/s upwards
D)0.350 kg ∙ m/s upwards
E)0.350 kg ∙ m/s downwards

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Multiple Choice

Q 174Q 174

A 0.32-kg ball is moving horizontally at 30 m/s just before suddenly bouncing off a wall Just after the bounce, it is moving horizontally at 25 m/s but in the opposite direction.
(a)What is the magnitude of the change in momentum of the ball during the bounce?
(b)What percentage of the ball's original kinetic energy was lost in the collision?

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Q 175Q 175

In a police ballistics test, a 2.00-g bullet suddenly hits and becomes embedded in a 5.00-kg wood block which is hanging from a 1.20-m long string. This causes the block to swing through an arc of 3.50°. What was the speed of the bullet just before it hit the block?
A)16.7 m/s
B)524 m/s
C)25.3 m/s
D)262 m/s
E)789 m/s

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Multiple Choice

Q 176Q 176

A block of mass m = 9.0 kg and speed V and is behind a block of mass M = 27 kg and speed of as shown int the figure. The surface is frictionless, and the blocks suddenly collide and couple. After the collision, the blocks have a common speed of 0.90 m/s. How much kinetic energy of the blocks is lost due to the collision?
A)8.6 J
B)2.0 J
C)4.6 J
D)11 J
E)31 J

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Multiple Choice

Q 177Q 177

As shown in the figure, a bullet of mass 0.010 kg moving horizontally suddenly strikes a block of wood of mass 1.5 kg that is suspended as a pendulum. The bullet lodges in the wood, and together they swing upward a vertical distance of 0.40 m. The length of the string is 2.0 m. What was the speed of the bullet just before it struck the wooden block?
A)67 m/s
B)250 m/s
C)370 m/s
D)420 m/s
E)650 m/s

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Multiple Choice

Q 178Q 178

An 8.0-g bullet is suddenly shot into a 4.0-kg block that is at rest on a frictionless horizontal surface, as shown in the figure. The bullet remains lodged in the block. The block then moves against a spring and compresses it by 3.7 cm. The force constant (spring constant)of the spring is What was the initial speed v of the bullet?
A)460 m/s
B)440 m/s
C)480 m/s
D)500 m/s
E)520 m/s

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Multiple Choice

Q 179Q 179

An 8.0-g bullet is suddenly shot into a 4.0-kg block, at rest on a frictionless horizontal surface, as shown in the figure. The bullet remains lodged in the block. The block then moves against a spring and compresses it by 8.9 cm. The force constant (spring constant)of the spring is What is the magnitude of the impulse on the block (including the bullet inside)due to the spring during the entire time interval during which the block compresses the spring?
A)13 N ∙ s
B)12 N ∙ s
C)10 N ∙ s
D)8.3 N ∙ s
E)6.7 N ∙ s

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Multiple Choice

Q 180Q 180

In a police rifle test, a 15-g bullet traveling 213 m/s in a vertical direction suddenly buries itself in a 2.4-kg block of wood at rest directly above it. As a result, the bullet-block combination moves vertically upward.
(a)Determine the velocity of the bullet-block combination just after the impact.
(b)Determine the maximum height reached by the bullet/block combination.
(c)Is kinetic energy conserved in this collision?

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Q 181Q 181

In a certain nuclear reactor, neutrons suddenly collide with deuterons, which have twice the mass of neutrons. In a head-on elastic collision with a stationary deuteron, what fraction of the initial kinetic energy of a neutron is transferred to the deuteron?
A)1/2
B)1/3
C)3/4
D)5/6
E)8/9

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Multiple Choice

Q 182Q 182

In a certain nuclear reactor, neutrons suddenly collide with carbon nuclei, which have 12 times the mass of neutrons. In a head-on elastic collision with a stationary carbon nucleus, what fraction of its initial speed does the neutron have after the collision?
A)11/12
B)1/12
C)11/13
D)5/6
E)10/13

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Multiple Choice

Q 183Q 183

An object initially at rest suddenly explodes in two fragments of masses and that move in opposite directions. If the speed of the first fragment is find the internal energy of the explosion.
A)30 J
B)30 kJ
C)38 J
D)38 kJ

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Multiple Choice

Q 184Q 184

Two simple pendulums of equal length l = 0.45 m are suspended from the same point. The pendulum bobs are small solid steel spheres. The first bob is drawn back to make a 35° angle with the vertical, while the other one is left hanging at rest. If the first bob has a mass of 0.25 kg and the second has a mass of how high will the second bob rise above its initial position when struck elastically by the first bob after it is released?
A)3.3 cm
B)2.7 cm
C)3.9 cm
D)4.4 cm

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Multiple Choice

Q 185Q 185

On a frictionless horizontal surface, a 1.50-kg mass traveling at 3.50 m/s suddenly collides with and sticks to a 3.00-kg mass that is initially at rest, as shown in the figure. This system then runs into an ideal spring of force constant (spring constant)50.0 N/cm.
(a)What will be the maximum compression distance of the spring?
(b)How much mechanical energy is lost during this process? During which parts of the process (the collision and compression of the spring)is this energy lost?

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Q 186Q 186

A baseball pitcher is employing a ballistic pendulum to determine the speed of his fastball. A lump of clay is suspended from a cord 2.0 m long. When the pitcher throws his fastball aimed directly at the clay, the ball suddenly becomes embedded in the clay and the two swing up to a maximum height of 0.080 m. If the mass of the baseball is 0.21 kg, find the speed of the pitched ball.

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Q 187Q 187

A 1200-kg pick-up truck traveling south at 15 m/s suddenly collides with a 750-kg car that is traveling east. The two vehicles stick together and slide along the road after colliding. A highway patrol officer investigating the accident determines that the final position of the wreckage after the collision is 25 m, at an angle of 50° south of east, from the point of impact. She also determines that the coefficient of kinetic friction between the tires and the road at that location was 0.40. What was the speed of the car just before the collision?
A)20 m/s
B)4.8 m/s
C)14 m/s
D)23 m/s
E)17 m/s

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Multiple Choice

Q 188Q 188

A uniform solid cylinder with a radius of 10 cm and a mass of 3.0 kg is rotating about its center with an angular speed of 33.4 rpm. What is its kinetic energy?
A)0.18 J
B)0.092 J
C)0.96 J
D)1.1 J
E)17 J

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Multiple Choice

Q 189Q 189

What is the kinetic energy of a 120-cm thin uniform rod with a mass of 450 g that is rotating about its center at 3.60 rad/s?
A)0.350 J
B)4.20 J
C)0.700 J
D)0.960 J
E)2.10 J

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Multiple Choice

Q 190Q 190

To drive a typical car at 40 mph on a level road for one hour requires about 3.2 × 10

^{7}J of energy. Suppose we tried to store this much energy in a spinning, solid, uniform, cylindrical flywheel. A large flywheel cannot be spun too fast or it will fracture. If we used a flywheel of diameter 1.2 m and mass 400 kg, what angular speed would be required to store 3.2 × 10^{7}J? A)1800 rad/s B)3600 rad/s C)940 rad/s D)530 rad/s E)5500 rad/sFree

Multiple Choice

Q 191Q 191

The L-shaped object shown in the figure consists of three small masses connected by extremely light rods. Assume that the masses shown are accurate to three significant figures. How much work must be done to accelerate the object from rest to an angular speed of 3.25 rad/s (a)about the x-axis, (b)about the y-axis?

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Q 192Q 192

The L-shaped object shown in the figure consists of three small masses connected by thin uniform rods, each rod of mass 3.00 kg. Assume that the masses shown are accurate to three significant figures. How much work must be done to accelerate the object from rest to an angular speed of 3.25 rad/s about the y-axis?

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Q 193Q 193

A futuristic design for a car is to have a large flywheel within the car to store kinetic energy. The flywheel is a solid uniform disk of mass 370 kg with a radius of 0.50 m, and it can rotate up to Assuming all of this stored kinetic energy could be transferred to the linear speed of the car, find the maximum attainable speed of the car.

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Essay

Q 194Q 194

A small ball is tied to one end of a light 2.5-m wire, and the other end of the wire is hooked to the ceiling. A person pulls the ball to the side until the wire makes an angle of 35° with the plane of the ceiling and then gently releases it. What is the angular speed of the ball, in rad/s, as it swings through its lowest point?

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Q 195Q 195

While spinning down from 500 rpm to rest, a flywheel does of work. This flywheel is in the shape of a solid uniform disk of radius 1.2 m. What is the mass of this flywheel?
A)4.0 kg
B)3.4 kg
C)4.6 kg
D)5.2 kg

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Multiple Choice

Q 196Q 196

A solid uniform sphere of mass 120 kg and radius 1.7 m starts from rest and rolls without slipping down an inclined plane of vertical height 5.3 m. What is the angular speed of the sphere at the bottom of the inclined plane?
A)5.1 rad/s
B)8.7 rad/s
C)9.7 rad/s
D)6.1 rad/s

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Multiple Choice

Q 197Q 197

A solid uniform disk of diameter 3.20 m and mass 42 kg rolls without slipping to the bottom of a hill, starting from rest. If the angular speed of the disk is 4.27 rad/s at the bottom, how high did it start on the hill?
A)3.57 m
B)2.68 m
C)3.14 m
D)4.28 m

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Multiple Choice

Q 198Q 198

A wheel having a moment of inertia of 5.00 kg ∙ m

^{2}starts from rest and accelerates under a constant torque of 3.00 N ∙ m for 8.00 s. What is the wheel's rotational kinetic energy at the end of 8.00 s? A)57.6 J B)64.0 J C)78.8 J D)122 JFree

Multiple Choice

Q 199Q 199

As shown in the figure, two blocks are connected by a light string that passes over a frictionless pulley having a moment of inertia of 0.0040 kg ∙ m

^{2}and diameter 10 cm. The coefficient of kinetic friction between the table top and the upper block is 0.30. The blocks are released from rest, and the string does not slip on the pulley. How fast is the upper block moving when the lower one has fallen 0.60 m? A)1.2 m/s B)5.4 m/s C)3.2 m/s D)2.0 m/s E)1.4 m/sFree

Multiple Choice

Q 200Q 200

A solid uniform ball with a mass of 125 g is rolling without slipping along the horizontal surface of a table with a speed of 4.5 m/s when it rolls off the edge and falls towards the floor, 1.1 m below. What is the rotational kinetic energy of the ball just before it hits the floor?
A)0.51 J
B)0.73 J
C)1.1 J
D)2.6 J
E)This question cannot be answered without knowing the radius of the ball.

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Multiple Choice

Q 201Q 201

A string is wrapped tightly around a fixed pulley that has a moment of inertia of 0.0352 kg ∙ m

^{2}and a radius of 12.5 cm. A mass of 423 g is attached to the free end of the string. With the string vertical and taut, the mass is gently released so it can descend under the influence of gravity. As the mass descends, the string unwinds and causes the pulley to rotate, but does not slip on the pulley. What is the speed of the mass after it has fallen through 1.25 m? A)2.00 m/s B)2.28 m/s C)1.97 m/s D)3.94 m/s E)4.95 m/sFree

Multiple Choice

Q 202Q 202

A string is wrapped tightly around a fixed frictionless pulley that has a moment of inertia of 0.0352 kg ∙ m

^{2}and a radius of 12.5 cm. The string is pulled away from the pulley with a constant force of 5.00 N, causing the pulley to rotate. What is the speed of the string after it has unwound 1.25 m if the string does not slip on the pulley? A)2.09 m/s B)2.36 m/s C)1.18m/s D)3.18 m/s E)4.95 m/sFree

Multiple Choice

Q 203Q 203

An Atwood machine consists of a mass of 3.5 kg connected by a light string to a mass of 6.0 kg over a frictionless pulley with a moment of inertia of 0.0352 kg ∙ m

^{2}and a radius of 12.5 cm. If the system is released from rest, what is the speed of the masses after they have moved through 1.25 m if the string does not slip on the pulley? A)2.0 m/s B)2.3 m/s C)4.0 m/s D)5.0 m/s E)6.0 m/sFree

Multiple Choice

Q 204Q 204

The figure shows two blocks connected by a light cord over a pulley. This apparatus is known as an Atwood's machine. There is no slipping between the cord and the surface of the pulley. The pulley itself has negligible friction and it has a radius of 0.12 m and a mass of 10.3 kg. We can model this pulley as a solid uniform disk. At the instant that the heavier block has descended 1.5 m starting from rest, what is the speed of the lighter block?

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Q 205Q 205

A pencil that is 15.7 cm long is released from a vertical position with the eraser end resting on a table. The eraser does not slip as it tips over. Treat the pencil like a uniform rod. What is the angular speed of the pencil just before it hits the table?
A)13.7 rad/s
B)7.23 rad/s
C)3.70 rad/s
D)24.5 rad/s
E)16.8 rad/s

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Multiple Choice

Q 206Q 206

A uniform solid disk is released from rest and rolls without slipping down an inclined plane that makes an angle of 25° with the horizontal. What is the forward speed of the disk after it has rolled 3.0 m, measured along the plane?
A)2.0 m/s
B)3.5 m/s
C)4.1 m/s
D)5.7 m/s
E)6.3 m/s

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Multiple Choice

Q 207Q 207

A solid uniform disk is rolling without slipping along a horizontal surface with a speed of 4.5 m/s when it starts up a ramp that makes an angle of 25° with the horizontal. What is the speed of the disk after it has rolled 3.0 m up as measured along the surface of the ramp?
A)4.0 m/s
B)1.9 m/s
C)2.1 m/s
D)6.8 m/s
E)8.0 m/s

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Multiple Choice

Q 208Q 208

A solid uniform sphere is rolling without slipping along a horizontal surface with a speed of 5.5 m/s when it starts up a ramp that makes an angle of 25° with the horizontal. What is the speed of the sphere after it has rolled 3.0 m up as measured along the surface of the ramp?
A)4.0 m/s
B)8.0 m/s
C)1.9 m/s
D)2.2 m/s
E)3.5 m/s

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Multiple Choice

Q 209Q 209

A hoop is rolling without slipping along a horizontal surface with a forward speed of 5.50 m/s when it starts up a ramp that makes an angle of 25.0° with the horizontal. What is the speed of the hoop after it has rolled 3.00 m up as measured along the surface of the ramp?
A)4.22 m/s
B)1.91 m/s
C)2.06 m/s
D)3.79 m/s
E)8.02 m/s

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Multiple Choice

Q 210Q 210

A hoop with a mass of 2.75 kg is rolling without slipping along a horizontal surface with a speed of 4.5 m/s when it starts down a ramp that makes an angle of 25° below the horizontal. What is the forward speed of the hoop after it has rolled 3.0 m down as measured along the surface of the ramp?
A)4.9 m/s
B)6.3 m/s
C)5.2 m/s
D)5.7 m/s
E)8.0 m/s

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Multiple Choice

Q 211Q 211

A hoop with a mass of 2.75 kg is rolling without slipping along a horizontal surface with a speed of 4.5 m/s when it starts down a ramp that makes an angle of 25° below the horizontal. What is the rotational kinetic energy of the hoop after it has rolled 3.0 m down as measured along the surface of the ramp?
A)34 J
B)22 J
C)45 J
D)62 J
E)This question cannot be answered without knowing the radius of the hoop.

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Multiple Choice

Q 212Q 212

A solid uniform 3.33-kg disk has thin string of negligible mass wrapped around its rim, with one end of the string tied to the ceiling, as shown in the figure. The disk is released from rest, and as it falls, it turns as the string unwraps. At the instant its center has fallen 2.25 m, (a)how fast is the center moving, and (b)how much rotational kinetic energy does the disk have?

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Q 213Q 213

A solid uniform ball of mass 1.0 kg and radius 1.0 cm starts from rest and rolls down a 1.0-m high ramp. There is enough friction on the ramp to prevent the ball from slipping as it rolls down.
(a)What is the forward speed of the ball when it reaches the bottom of the ramp?
(b)What would be the forward speed of the ball if there were no friction on the ramp?
(c)Since the ball starts from the same height in both cases, why is the speed different?

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Q 214Q 214

A solid ball of mass 1.0 kg and radius 10 cm rolls with a forward speed of 10 m/s when it comes to a hill. There is enough friction on the hill to keep the ball from slipping as it rolls up.
(a)How high vertically up the hill can the ball roll before coming to rest?
(b)How high vertically could the ball go if the hill were totally frictionless?
(c)How is it that the ball can go higher with friction than without friction?

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Q 215Q 215

A ball in the shape of a uniform spherical shell (like a soccer ball)of mass 1.5 kg and radius 15 cm rolls down a 35° incline that is 6.0 m high, measured vertically. The ball starts from rest, and there is enough friction on the incline to prevent slipping of the ball.
(a)How fast is the ball moving forward when it reaches the bottom of the incline, and what is its angular speed at that instant?
(b)If there were no friction on the incline, how fast would the ball be moving forward and what would be its angular speed at the bottom?

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Q 216Q 216

A solid uniform cylinder is rolling without slipping. What fraction of its kinetic energy is rotational?
A)1/3
B)2/3
C)1/2
D)1/4
E)3/4

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Multiple Choice

Q 217Q 217

NASA puts a satellite into space that consists of two small 32-kg balls connected by a 12-m long light cable, as shown in the figure. The entire system is initially rotating at 4.0 rpm about an axis perpendicular to the cable at the center of mass. Motors in each mass reel out more cable so that the masses double their separation to 24 m.
(a)What is the final rotational speed (in rpm)of the balls?
(b)If the initial rotational kinetic energy of the system was K, what is the final rotational kinetic energy in terms of K?

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Q 218Q 218

A uniform ball with diameter of 10 cm rolls without slipping on a horizontal tabletop. The moment of inertia of the ball about an axis through its center is 2.2 × 10

^{-3}kg ∙ m^{2}, and the translational speed of its center is 0.45 m/s. (a)What is its angular speed of the ball about its center of mass? (b)What is the rotational kinetic energy of the ball? (c)What is the ball's angular momentum about its center of mass?Free

Essay

Q 219Q 219

A solid wooden door, 90 cm wide by 2.0 m tall, has a mass of 35 kg. It is open and at rest. A small 500-g ball is thrown perpendicular to the door with a speed of 20 m/s and hits the door 60 cm from the hinged side, causing it to begin turning. The ball rebounds along the same line with a speed of 16.0 m/s relative to the ground. How much energy is lost during this collision?
A)30 J
B)16 J
C)15 J
D)13 J
E)4.8 J

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Multiple Choice