Deck 11: Rotational Dynamics and Static Equilibrium

Question 1

A child runs and jumps tangentially onto an initially stationary playground merry-go-round. As a result, the merry-go-round begins to turn. Explain in terms of the child-merry-go-round system.

Answer 1

The child has an initial angular momentum about the center of the merry-go-round.The total angular momentum of the system is conserved,so the merry-go-round must rotate when the child is on it.

Question 2

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. What happens to the puck's angular speed?

Answer 2

The tension in the string is directed towards the center,so there is no torque about the center.Thus,its angular speed has to increase to keep the angular momentum constant.

Question 3

Two equal forces are applied to a door at the doorknob. The first force is applied perpendicular to the door; the second force is applied at 30° to the plane of the door. Which force exerts the greater torque?

A) the first applied perpendicular to the door
B) the second applied at an angle
C) both exert equal non-zero torques
D) both exert zero torques
E) Additional information is needed.

Answer 3

the first applied perpendicular to the door

Question 4

If you stand with your back towards a wall and your heels touching the wall, you cannot lean over to touch your toes. Why?

Question 5

The attraction of the Moon causes tides on Earth. Because of friction, tidal action slows the rotation of Earth. What happens to the angular momentum of the Earth-Moon system, and does this affect the motion of the moon?

Question 6

In recent years, many planetary systems have been discovered around distant stars. This has been accomplished, not by direct observation of the planets themselves, but indirectly, by observing a wobbling motion in the star. Why is this wobbling motion evidence of a planet?

Question 7

Jane says that the magnitude of the torque exerted by a force of magnitude F is equal to the perpendicular distance from the axis of rotation r_⊥ multiplied by F, while Jason insists that it is equal to the distance from the axis of rotation r multiplied by the magnitude of the perpendicular component of the force, F_⊥. Who is right?

Question 8

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. What happens to the puck's linear speed?

Question 9

Two equal forces are applied to a door. The first force is applied at the midpoint of the door; the second force is applied at the doorknob. Both forces are applied perpendicular to the door. Which force exerts the greater torque?

A) the first at the midpoint
B) the second at the doorknob
C) both exert equal non-zero torques
D) both exert zero torques
E) Additional information is needed.

Question 10

When a car decelerates, its front end goes down. Explain.

Question 11

Why is it recommended that if you are lifting a heavy object you should lift it as close to your body as possible?

Question 12

Some students are discussing why a simple Atwood machine accelerates. Jane says that because of the unequal masses, gravity exerts a constant external torque on the two-mass and pulley system and thus its total angular momentum increases at a constant rate. Is Jane's explanation a valid one?

Question 13

A child is riding near the outer rim of a freely-rotating playground merry-go-round. What happens if the child walks towards the center?

Question 14

State the conditions for static equilibrium.

Question 15

If the net force on an object is zero N, does the net torque on the object have to be zero Nm?

Question 16

A puck moves on a horizontal air table. It is attached to a string that gradually winds itself up around a round peg in the center of the table. This shortens the string, so the puck gradually spirals in towards the center. What happens to the magnitude of the puck's angular momentum?

Question 17

In a model airplane, the propeller is a significant part of the total mass. A model airplane is flying on a level path, with its propeller rotating clockwise as seen facing the airplane. At a preset time, a signal causes the plane to lower its tail flaps and it goes into a nose-down attitude. When this happens, the nose of the plane also swings towards the right. Explain why this happens.

Question 18

Can two different forces, acting through the same point, produce the same torque on an object?

Question 19

An object in motion with constant speed along a straight line can never have nonzero angular momentum.

Question 20

Tightrope walkers often employ a long pole to help them retain their balance. What advantage is there to using a very flexible pole so that the ends droop?

Question 21

A heavy boy and a lightweight girl are balanced on a massless seesaw. If they both move forward so that they are one-half their original distance from the pivot point, what will happen to the seesaw?

A) It is impossible to say without knowing the masses.
B) It is impossible to say without knowing the distances.
C) The side the boy is sitting on will tilt downward.
D) Nothing, the seesaw will still be balanced.
E) The side the girl is sitting on will tilt downward.

Question 22

As you are leaving a building, the door opens outward. If the hinges on the door are on your right, what is the direction of the angular velocity of the door as you open it?

A) up
B) down
C) to your left
D) to your right
E) forwards

Question 23

You are walking holding on to the axle of a spinning bicycle wheel with one hand on either side of the wheel. The top part of the wheel is moving away from you and the bottom is moving toward you and the axle is horizontal. As you start to turn left, you feel the right side of the axle

A) push on your right hand toward the left.
B) push on your right hand toward you.
C) pull on your right hand away from you.
D) push on your right hand vertically up.
E) push on your right hand vertically down.

Question 24

A person sits on a freely spinning lab stool (no friction). When this person extends her arms,

A) her moment of inertia decreases and her angular velocity increases.
B) her moment of inertia decreases and her angular velocity decreases.
C) her moment of inertia increases and her angular velocity increases.
D) her moment of inertia increases and her angular velocity decreases.
E) her moment of inertia increases and her angular velocity remains the same.

Question 25

FIGURE 11-2
A croquet mallet balances when suspended from its center of mass, as shown in Figure 11-2. If you cut the mallet in two at its center of mass, as shown, how do the masses of the two pieces compare?

A) The masses are equal.
B) The piece with the head of the mallet has the greater mass.
C) The piece with the head of the mallet has the smaller mass.
D) It is impossible to tell.

Question 26

An ice skater doing a spin pulls in her arms, decreasing her moment of inertia by a factor of two. How does her angular speed changes?

A) It is reduced by a factor of two.
B) It is reduced by a factor of four.
C) It increases by a factor of two.
D) It increases by a factor of four.
E) It doesn't change.

Question 27

A merry-go-round spins freely when Janice moves quickly to the center along a radius of the merry-go-round. 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.

Question 28

When a car is weighed, it is allowed to move over a scale which records a reading as the front wheels go over the scale, and a second reading when the rear wheels go over the scale. The weight of the car is equal to

A) the weight under the front wheels.
B) the weight under the rear wheels.
C) the average of the two weights.
D) the sum of the two weights.
E) the difference of the two weights.

Question 29

You are holding a finishing sander with your right hand. The sander has a flywheel which spins counterclockwise as seen from behind the handle. You are sanding a wall in front of you. As you turn the sander towards the right, you feel a tendency in the sander to

A) turn towards the left.
B) turn upward.
C) turn downward.
D) push toward you.
E) pull away from you.

Question 30

FIGURE 11-2
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 by 1/2?

A) 2
B) 4
C)
D) 1
E) 1/2

Question 31

FIGURE 11-1
The rotating systems shown in Figure 11-1 differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest,

A) the block at left lands first.
B) the block at right lands first.
C) both blocks land at the same time.
D) it is impossible to tell which block reaches the bottom first.

Question 32

FIGURE 11-1
The rotating systems shown in Figure 11-1 differ only in that the two identical movable masses are positioned a distance r from the axis of rotation (left), or a distance r/2 from the axis of rotation (right). If you release the hanging blocks simultaneously from rest, and call t_L the time taken by the block on the left and t_R the time taken by the block on the right to reach the bottom, respectively, then

A) t_L = t_R.
B) t_L = t_R.
C) t_L = t_R.
D) t_L = 2 t_R.
E) t_L = 4t_R.

Question 33

Two forces are applied to a doorknob, perpendicular to the door. The first force is twice as large as the second force. The ratio of the torque of the first to the torque of the second is

A) 1/4.
B) 1/2.
C) 2.
D) 4.
E) 8.

Question 34

FIGURE 11-2
A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her angular speed increases dramatically. The speed increase is a demonstration of

A) conservation of energy: her moment of inertia is decreased, and so her angular speed must increase to conserve energy.
B) conservation of angular momentum: her moment of inertia is decreased, and so her angular speed must increase to conserve angular momentum.
C) Newton's second law for rotational motion: she exerts a torque and so her angular speed increases.
D) This has nothing to do with mechanics, it is simply a result of her natural ability to perform.

Question 35

FIGURE 11-2
A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her moment of inertia decreases by 1/2. By what factor does her rotational kinetic energy change?

A) 2
B) 4
C)
D) 1/2
E) It doesn't change.

Question 36

When you ride a bicycle, in what direction is the angular velocity of the wheels?

A) to your left
B) to your right
C) forwards
D) backwards
E) up

Question 37

FIGURE 11-3
A mill grinds corn by means of a grinding wheel attached to a long horizontal axle that is hinged to a vertical rotating axle as shown in Figure 11-3. The rotation of the vertical axle forces the horizontal axle to follow it. Thus, the wheel moves in a circular path, and its motion makes it rotate. The wheel then crushes the corn in its path. The force exerted by the wheel on the corn is

A) equal to the weight of the wheel.
B) greater than the weight of the wheel.
C) less than the weight of the wheel.
D) There is not enough information to answer this question.

Question 38

FIGURE 11-2
A figure skater is spinning slowly with arms outstretched. She brings her arms in close to her body and her moment of inertia decreases by 1/2. Her angular speed increases by a factor of

A) 2.
B) 4.
C) .
D) 1
E) 1/2.

Question 39

FIGURE 11-2
Angular momentum cannot be conserved if

A) the angular acceleration changes.
B) the angular velocity changes.
C) there is a net force on the system.
D) the moment of inertia changes.
E) the net torque is not zero.

Question 40

You are holding on to the axle of a spinning bicycle wheel with one hand on either side of the wheel. The top part of the wheel is moving away from you and the bottom is moving toward you and the axle is horizontal. In what direction do you need to apply a torque for the wheel to turn to the left?

A) toward you
B) away from you
C) vertically up
D) vertically down
E) to your right

Question 41

A light board, 10 m long, is supported by two sawhorses, one at one edge of the board and a second at the midpoint. A 40-N weight is placed between the two sawhorses, 3.0 m from the edge and 2.0 m from the center. What forces are exerted by the sawhorses on the board?

Question 42

A mechanic is examining the wheel of a bicycle to adjust the brake. With the bicycle off the ground, he manually rotates the wheel until it reaches an angular speed of 12.0 rad/s and then allows it to coast to a stop. If the wheel has a moment of inertia of 0.100 kg∙m², and the wheel slows to a stop in 160 s, what is the magnitude of the retarding torque?

A) 1.00 Nm
B) 0.00750 Nm
C) 0.0787Nm
D) 1.33 Nm
E) 1.67 Nm

Question 43

FIGURE 11-4
The mobile shown in Figure 11-4 is perfectly balanced. What must be the masses of m₁, m₂, and m₃?

Question 44

A man is holding an 8.00-kg vacuum cleaner at arm's length, a distance of 0.550 m from his shoulder. What is the torque on the shoulder joint if the arm is horizontal?

A) 0.242 Nm
B) 4.40 Nm
C) 43.2 Nm
D) 14.5 Nm
E) 0 Nm

Question 45

A man is holding an 8.00-kg vacuum cleaner at arm's length, a distance of 0.550 m from his shoulder. What is the torque on the shoulder joint if the arm is held at 30.0° below the horizontal?

A) 21.6 Nm
B) 2.20 Nm
C) 4.40 Nm
D) 12.6 Nm
E) 37.4 Nm

Question 46

A ball with diameter 10. cm rolls without slipping on a horizontal table top. The moment of inertia of the ball is 2.2 × 10^-3 kg- m² and its translational speed is 0.45 m/s.
(a) What is its angular speed about its center of mass?
(b) What is its rotational kinetic energy?
(c) What is its angular momentum?

Question 47

A horizontal 2.00-m long, 5.00-kg uniform beam that lies along the east-west direction is acted on by two forces. At the east end of the beam, a 200-N forces pushes downward. At the west end of the beam, a 200-N force pushed upward. What is the angular acceleration of the beam?

A) 240 rad/s² north
B) 1.33 × 10² rad/s² north
C) zero
D) 240 rad/s² south
E) 1.33 × 10² rad/s² south

Question 48

In a lab experiment, a student brings up the rotational speed of a rotational motion apparatus to 30.0 rpm. She then allows the apparatus to slow down on its own, and counts 240 revolutions before the apparatus comes to a stop. The moment of inertia of the flywheel is 0.0850 kg∙m². What is the retarding torque on the flywheel?

A) 0.0425 Nm
B) 0.159 Nm
C) 0.0787Nm
D) 0.000278 Nm
E) 0.0000136 Nm

Question 49

Consider a bicycle wheel to be a ring of radius 30. cm and mass 1.5 kg. Neglect the mass of the axle and sprocket. If a force of 20. N is applied tangentially to a sprocket of radius 4.0 cm for 4.0 s, what linear speed does the wheel achieve, assuming it rolls without slipping?

Question 50

A 82.0 kg painter stands on a long horizontal board 1.55 m from one end. The 15.5 kg board is 5.50 m long. The board is supported at each end.
(a) What is the total force provided by both supports?
(b) With what force does the support, closest to the painter, push upward?

Question 51

A horizontal, 2.00 m long, 3.00 kg uniform beam that lies along the east-west direction is acted on by two forces. At the east end of the beam, a 200 N force pushes downward. At the west end of the beam, a 200 N force pushed upward. What is the torque about the center of mass of the beam?

A) 800 N∙m north
B) zero
C) 400 N∙m north
D) 800 N∙m south
E) 400 N∙m south

Question 52

The drive chain in a bicycle is applying a torque of 0.850 Nm to the wheel of the bicycle. The wheel has a moment of inertia of 0.100 kg∙m². What is the angular acceleration of the wheel?

Question 53

A light board, 10 m long, is supported by two sawhorses, one at one edge of the board and a second at the midpoint. A 40-N weight is placed between the two sawhorses, 3.0 m from the edge and 2.0 m from the center. A second weight, with a weight of 15 N, is placed on the far end from the board. What forces are exerted by the sawhorses on the board?

Question 54

A ballerina spins initially at 1.5 revolutions/second when her arms are extended. She then draws in her arms to her body and her moment of inertia becomes 0.88 kg- and her angular speed increases to 4.0 rev/s. Determine her initial moment of inertia.

Question 55

The drive chain in a bicycle is applying a torque of 0.850 Nm to the wheel of the bicycle. Treat the wheel as a hoop with a mass of 0.750 kg and a radius of 33.0 cm. What is the angular acceleration of the wheel?

A) 10.4 rad/s²
B) 20.8 rad/s²
C) 5.20 rad/s²
D) 3.43 rad/s²
E) 1.06 rad/s²

Question 56

A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What force, applied 0.300 m on the other side of the pivot, is needed to make the child lift off the ground?

A) 75.0 N
B) 736 N
C) 22.5 N
D) 44.1 N
E) 66.2 N

Question 57

A 15.0-kg child is sitting on a playground teeter-totter, 1.50 m from the pivot. What is the minimum distance, on the other side of the pivot, such that a 220-N force will make the child lift off the ground?

A) 1.00 m
B) 1.50 m
C) 0.102 m
D) 9.78 m
E) 2.35 m

Question 58

A girl weighing 450. N sits on one end of a seesaw that is 3.0 m long and is pivoted 1.3 m from the girl. If the seesaw is just balanced when a boy sits at the opposite end, what is his weight?
Neglect the weight of the seesaw.

Question 59

A diver can change her rate of rotation in the air by "tucking" her head in and bending her knees. Let's assume that when she is stretched out straight she is rotating at 1 revolution per second. Now she goes into the "tuck and bend," effectively shortening the length of her body by half. What will her rate of rotation be now?

Question 60

A 1.8 kg solid disk pulley of radius 0.11 m rotates about an axis through its center.
(a) What is its moment of inertia?
(b) Starting from rest, a torque of 0.22 m-N will produce what angular acceleration?

Question 61

A 350-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of inertia of 6.00 × 10^-6 kg∙m² and a radius of 1.35 cm. The string is pulled vertically downward by a force of 2.50 N. What is the tension in the string between the pulley and the cart?

A) 4.58 N
B) 2.50 N
C) 1.85 N
D) 2.29 N
E) 1.74 N

Question 62

A truck is carrying a 120-kg refrigerator, which is 2.20 m tall and 85.0 cm wide has its center of mass at its geometrical center. The refrigerator is facing sideways and a short strip on the bed of the truck keeps the refrigerator from sliding. What is the maximum acceleration that the truck can have before the refrigerator begins to tip over?

A) 1.90 m/s²
B) 4.17 m/s²
C) 3.79 m/s²
D) 7.58 m/s²
E) 8.34 m/s²

Question 63

A 320-g mass and a 400-g mass are attached to the two ends of a string that goes over a pulley with a radius of 8.70 cm. Because of friction, the pulley does not begin to rotate. What is the magnitude of the frictional torque on the bearing of the pulley if the system is in static equilibrium?

A) 0.00683 Nm
B) 0.614 Nm
C) 0.0787 Nm
D) 0.0626 Nm
E) 0.000696 Nm

Question 64

A 120-kg refrigerator, 2.00 m tall and 85.0 cm wide has its center of mass at its geometrical center. You are attempting to slide it along the floor by pushing horizontally on the side of the refrigerator. The coefficient of static friction between the floor and the refrigerator is 0.300. Depending on where you push, the refrigerator may start to tip over before it starts to slide along the floor. What is the highest distance above the floor that you can push the refrigerator so that it won't tip before it begins to slide?

A) 0.710 m
B) 1.00 m
C) 1.21 m
D) 1.42 m
E) 1.63 m

Question 65

A 350-g air track cart on a horizontal air track is attached to a string that goes over a pulley with a moment of inertia of 6.00 × 10^-6 kg∙m² and a radius of 1.35 cm. The string is pulled vertically downward by a force of 2.50 N. What is the acceleration of the cart?

A) 7.14 m/s²
B) 6.53 m/s²
C) 5.27 m/s²
D) 4.98 m/s²
E) 3.27 m/s²

Question 66

FIGURE 11-6
A store's sign, with a mass of 20.0 kg and 3.00 m long, has its center of gravity at the center of the sign. It is supported by a loose bolt attached to the wall at one end and by a wire at the other end, as shown in Figure 11-6. The wire makes an angle of 25.0° with the horizontal. What is the magnitude of the force exerted by the bolt on the sign?

A) 464 N
B) 232 N
C) 196 N
D) 116 N
E) 297 N

Question 67

FIGURE 11-6
A store's sign, with a mass of 20.0 kg and 3.00 m long, has its center of gravity at the center of the sign. It is supported by a loose bolt attached to the wall at one end and by a wire at the other end, as shown in Figure 11-6. The wire makes an angle of 25.0° with the horizontal. What is the tension in the wire?

A) 464 N
B) 232 N
C) 116 N
D) 196 N
E) 297 N

Question 68

The wheelbase on a 50,000-kg truck is 2.40 m wide and the truck's center of mass is located along the vertical centerline of the truck and 2.00 m above the bottom of the tires. The truck is going around a horizontal turn with a radius of 250 m at 24.0 m/s. What is the total normal force on the tires on the side of the truck that faces the center of the curve?

A) 245 kN
B) 149 kN
C) 349 kN
D) 283 kN
E) 255 kN

Question 69

A mass of 375 g hangs from a string that is wrapped around the circumference of a pulley with a moment of inertia of 0.0125 kg∙m² and a radius of 26.0 cm. When the mass is released, the mass accelerates downward and the pulley rotates about its axis as the string unwinds. What is the tension in the string?

A) 1.21 N
B) 2.45 N
C) 3.68 N
D) 1.84 N
E) 0.605 N

Question 70

A meter stick balances at the 50.0-cm mark. If a mass of 50.0 g is placed at the 90.0-cm mark, the stick balances at the 61.3-cm mark. What is the mass of the meter stick?

A) 127 g
B) 178 g
C) 89.7 g
D) 32.6 g
E) 73.4 g

Question 71

FIGURE 11-5
An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m apart, as shown in Figure 11-5. Find the force exerted by pillar A.

A) 1.71 kN downwards
B) 1.71 kN upwards
C) 2.51 kN downwards
D) 2.51 kN upwards
E) 3.44 kN upwards

Question 72

FIGURE 11-6
A 3.00-m-long ladder, weighing 200 N, rests against a smooth vertical wall with its base on a horizontal rough floor, a distance of 1.00 m away from the wall. If the center of mass of the ladder is 1.20 m from its base, what frictional force must the floor exert on the base of the ladder in order for the ladder to be in static equilibrium?

A) 93.3 N
B) 130 N
C) 28.3 N
D) 102 N
E) 150 N

Question 73

FIGURE 11-5
An 82.0 kg-diver stands at the edge of a light 5.00-m diving board, which is supported by two pillars 1.60 m apart, as shown in Figure 11-5. Find the force exerted by pillar B.

A) 1.71 kN downwards
B) 1.71 kN upwards
C) 2.51 kN downwards
D) 2.51 kN upwards
E) 3.44 kN upwards

Question 74

FIGURE 11-7
A child is trying to stack two uniform wooden blocks, 12 cm in length, so they will protrude as much as possible over the edge of a table, without tipping over, as shown in Figure 11-7. What is the maximum possible overhang distance?

A) 5 cm
B) 6 cm
C) 7 cm
D) 8 cm
E) 9 cm

Question 75

FIGURE 11-8
A stepladder consists of two halves, hinged at the top, and connected by a tie rod which keeps the two halves from spreading apart. In this particular instance, the two halves are 2.50 m long, the tie rod is connected to the center of each half and is 70.0 cm long. An 800-N person stands 3/5 of the way up the stepladder, as shown in Figure 11-8. Neglecting the weight of the ladder, and assuming that the ladder is resting on a smooth floor, what is the tension in the tie rod? Note:
To solve this problem you must "cut" the ladder in half and consider the equilibrium of forces and torques acting on each half of the ladder.

A) 140 N
B) 240 N
C) 280 N
D) 360 N
E) 560 N

Question 76

To determine the location of the center of mass of a car, the car is driven over a scale. When the front wheels are over the scale, the weight recorded by the scale is 5800 N, and when the rear wheels are over the scale, the scale reads 6500 N. The distance between the front and rear wheels is 3.20 m. How far behind the front wheels is the center of mass located?

A) 0.845 m
B) 1.50 m
C) 1.59 m
D) 1.69 m
E) 1.72 m

Question 77

The wheelbase on a 50,000-kg truck is 2.40 m wide and the truck's center of mass is located along the vertical centerline of the truck and 2.00 m above the bottom of the tires. The truck is going around a horizontal turn with a radius of 180 m. What is the maximum speed at which the truck can go around the curve without some of its tires lifting off the road?

A) 44.3 m/s
B) 38.2 m/s
C) 32.5 m/s
D) 28.2 m/s
E) 25.0 m/s

Question 78

The wheelbase on a truck is 2.4 m wide and the truck's center of mass is located along the vertical centerline of the truck and 2.0 m above the bottom of the tires. The truck is going around a banked turn, when it is forced to stop. What is the maximum slope that the bank can have such that the truck will not tip over?

A) 26°
B) 31°
C) 34°
D) 39°
E) 21°

Question 79

FIGURE 11-6
A 5.00-m-long ladder, weighing 200 N, rests against a smooth vertical wall with its base on a horizontal rough floor, a distance of 1.20 m away from the wall. The center of mass of the ladder is 2.50 m from its base, and the coefficient of static friction between the ladder and the floor is 0.200. How far up the ladder, measured along the ladder, can a 600-N person climb before the ladder begins to slip?

A) 1.50 m
B) 1.26 m
C) 1.05 m
D) 3.95 m
E) 4.56 m

Question 80

A mass of 375 g hangs from a string that is wrapped around the circumference of a pulley with a moment of inertia of 0.0125 kg∙m² and a radius of 26.0 cm. When the mass is released, the mass accelerates downward and the pulley rotates about its axis as the string unwinds. What is the acceleration of the mass?

A) 19.9 m/s²
B) 15.8 m/s²
C) 13.1 m/s²
D) 6.57 m/s²
E) 3.28 m/s²