Question 1

FIGURE 8-12  A 2-kg mass is moving along the x axis. The potential energy curve as a function of position is shown in Figure 8-12. The system is conservative. There is no friction.
-Refer to Figure 8-12. If the kinetic energy of the object at the origin is 12 J, what will be the speed of the object at 6.0 m along the +x-axis?

Accepted Answer

A)  2.0 m/s 
B)  2.2 m/s 
C)  2.5 m/s 
D)  2.7 m/s 
E)  3.0 m/s

Question 2

An object of mass m is held at a vertical height h from ground level. It is then released and falls under the influence of gravity. Which of the following statements is true in this situation? (Neglect air resistance.)

Accepted Answer

A)  The total energy of the object is decreasing. 
B)  The kinetic energy of the object is decreasing. 
C)  The potential energy of the object is increasing. 
D)  The total energy of the object is increasing. 
E)  The potential energy of the object is decreasing and the kinetic energy is increasing.

Question 3

FIGURE 8-1 
-You need to load a crate of mass m onto the bed of a truck. One possibility is to lift the crate straight up over a height h, equal to height of the truck's bed. The work done in this case is W1. The other possibility is to slide the crate up the frictionless ramp of length L as shown in Figure 8-1. In this case you perform work W2. What statement is true?

Accepted Answer

A)  W1 2 
B)  W1 = W2 
C)  W1 > W2 
D)  No simple relationship exists between W1 and W2.

Question 4

Any location can be chosen for potential energy equal to zero.

Accepted Answer

A) True 
 B)False

Question 5

A mass of 1.0 kg is pushed against a spring with a spring constant of 25 N/m. As a result, the spring is compressed by 20 cm. The mass is then released.
(a) What is the amount of potential energy acquired by the spring when it is compressed?
(b) What is the kinetic energy of the mass after the mass is released and it is no longer in contact with the spring?

Accepted Answer

The answer of A mass of 1.0 kg is pushed...

Question 6

FIGURE 8-6  A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/sS1U1P12S1S1P0.
-What is the total energy of the roller coaster at point B?

Accepted Answer

A)  16.4 × 103 J 
B)  20.2 × 103 J 
C)  17.6 × 104 J 
D)  16.4 × 104 J 
E)  There is not enough information to solve this problem.

Question 7

FIGURE 8-6  A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/sS1U1P12S1S1P0.
-What is the speed of the roller coaster at point B?

Accepted Answer

A)  66.3 m/s 
B)  20.0 m/s 
C)  46.9 m/s 
D)  17.6 m/s 
E)  There is not enough information to solve this problem.

Question 8

An object of mass 20.0 kg is lifted vertically through 1.00 m by a 400 N force. How much work is done by the net force in lifting this object? Use g = 10.0 m/s2.

Accepted Answer

A)  20.0 J 
B)  40.0 J 
C)  100 J 
D)  200 J 
E)  400 J

Question 9

The gravitational force is a conservative force.

Accepted Answer

A) True 
 B)False

Question 10

FIGURE 8-5  A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/sS1U1P12S1S1P0.
-Refer to Figure 8-5. What is the speed of the bead at point C?

Accepted Answer

A)  0 m/s 
B)  1.0 m/s 
C)  2.0 m/s 
D)  4.0 m/s 
E)  There is not enough information to solve this problem.

Question 11

FIGURE 8-7  Two masses MS1U1B11S1U1B0 = 2.0 kg and MS1U1B12S1U1B0 = 4.0 kg are attached by a string as shown in Figure 8-7. MS1U1B11S1U1B0 falls vertically down and MS1U1B12S1U1B0 moves on a frictionless surface. Initially the system is at rest. Use g = 10 m/sS1U1P12S1S1P0.
-Refer to Figure 8-7. What is the speed of mass M1 just before it touches the ground?

Accepted Answer

A)  2.3 m/s 
B)  2.9 m/s 
C)  3.8 m/s 
D)  4.6 m/s 
E)  5.8 m/s

Question 12

Kinetic energy may be positive or negative.

Accepted Answer

A) True 
 B)False

Question 13

An object moving along a horizontal surface approaches the bottom of a ramp. At the very bottom of the ramp, point A, its speed is 40 m/s. The object goes up the ramp and reverses direction at point B. What is the height of point B above point A? The angle of inclination is 30°. Neglect friction and use g = 10 m/s2.

Accepted Answer

A)  50 m 
B)  60 m 
C)  70 m 
D)  80 m 
E)  90 m

Question 14

An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will the object go before it comes to a stop? Use g = 10 m/s2.

Accepted Answer

A)  98 cm 
B)  61 m 
C)  98 m 
D)  23 m 
E)  61 cm

Question 15

What should the height of a slide in a park be so that a child will reach the bottom of the slide with a speed of 15.0 m/s? Use g = 10.0 m/s2.

Accepted Answer

A)  22.5 m 
B)  15.1 m 
C)  11.3 m 
D)  10.5 m 
E)  0.75 m

Question 16

A mass of 1.0 kg is pushed against a spring with a spring constant of 25 N/m. As a result, the spring is compressed by 20 cm. The mass is then released. What is the amount of work required to compress the spring?

Accepted Answer

The answer of A mass of 1.0 kg is pushed...

Question 17

FIGURE 8-9  An object with a mass of 10.0 kg is at rest at the top of a frictionless inclined plane of height 8.00 m and an angle of inclination 30.0° with the horizontal. The object is released from this position and it stops at a distance d from the bottom of the inclined plane along a horizontal surface, as shown in Figure 8-9. The coefficient of kinetic friction for the horizontal surface is 0.400 and g = 10.0 m/sS1U1P12S1S1P0.
-Refer to Figure 8-9. What is the kinetic energy of the object at the bottom of the inclined plane?

Accepted Answer

A)  400 J 
B)  500 J 
C)  700 J 
D)  800 J 
E)  900 J

Question 18

A force of 4.0 N applied to a spring compresses it by 8.0 cm. What is the amount of work done to compress the spring by an additional amount of 5.0 cm?

Accepted Answer

A)  20 J 
B)  0.26 J 
C)  0.50 J 
D)  2.0 J 
E)  50 N/m

Question 19

A snowboarder coasts on a smooth track that rises from one level to another. If the snowboarder's initial speed is 4 m/s, the snowboarder just makes it to the upper level and comes to rest. With a slightly greater initial speed of 5 m/s, the snowboarder is still moving to the right on the upper level. What is the snowboarder's final speed in this case?

Accepted Answer

A)  1 m/s 
B)  2 m/s 
C)  3 m/s 
D)  4 m/s 
E)  5 m/s

Question 20

An object of mass m with a certain initial speed on a horizontal surface comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the horizontal surface is 0.20, what is the initial speed of the object? Use g = 10 m/s2.

Accepted Answer

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

Exam 8: Potential Energy and Conservation of Energy

An object of mass m is held at a vertical height h from ground level. It is then released and falls under the influence of gravity. Which of the following statements is true in this situation? (Neglect air resistance.)

Any location can be chosen for potential energy equal to zero.

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s². -What is the total energy of the roller coaster at point B?

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s². -What is the speed of the roller coaster at point B?

An object of mass 20.0 kg is lifted vertically through 1.00 m by a 400 N force. How much work is done by the net force in lifting this object? Use g = 10.0 m/s².

The gravitational force is a conservative force.

FIGURE 8-5 A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s². -Refer to Figure 8-5. What is the speed of the bead at point C?

Kinetic energy may be positive or negative.

An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will the object go before it comes to a stop? Use g = 10 m/s².

What should the height of a slide in a park be so that a child will reach the bottom of the slide with a speed of 15.0 m/s? Use g = 10.0 m/s².

A mass of 1.0 kg is pushed against a spring with a spring constant of 25 N/m. As a result, the spring is compressed by 20 cm. The mass is then released. What is the amount of work required to compress the spring?

A force of 4.0 N applied to a spring compresses it by 8.0 cm. What is the amount of work done to compress the spring by an additional amount of 5.0 cm?

An object of mass m with a certain initial speed on a horizontal surface comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the horizontal surface is 0.20, what is the initial speed of the object? Use g = 10 m/s².

Exam 8: Potential Energy and Conservation of Energy

An object of mass m is held at a vertical height h from ground level. It is then released and falls under the influence of gravity. Which of the following statements is true in this situation? (Neglect air resistance.)

Any location can be chosen for potential energy equal to zero.

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s2. -What is the total energy of the roller coaster at point B?

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s2. -What is the speed of the roller coaster at point B?

An object of mass 20.0 kg is lifted vertically through 1.00 m by a 400 N force. How much work is done by the net force in lifting this object? Use g = 10.0 m/s2.

The gravitational force is a conservative force.

FIGURE 8-5 A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s2. -Refer to Figure 8-5. What is the speed of the bead at point C?

FIGURE 8-7 Two masses M1 = 2.0 kg and M2 = 4.0 kg are attached by a string as shown in Figure 8-7. M1 falls vertically down and M2 moves on a frictionless surface. Initially the system is at rest. Use g = 10 m/s2. -Refer to Figure 8-7. What is the speed of mass M1 just before it touches the ground?

Kinetic energy may be positive or negative.

An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will the object go before it comes to a stop? Use g = 10 m/s2.

What should the height of a slide in a park be so that a child will reach the bottom of the slide with a speed of 15.0 m/s? Use g = 10.0 m/s2.

A mass of 1.0 kg is pushed against a spring with a spring constant of 25 N/m. As a result, the spring is compressed by 20 cm. The mass is then released. What is the amount of work required to compress the spring?

A force of 4.0 N applied to a spring compresses it by 8.0 cm. What is the amount of work done to compress the spring by an additional amount of 5.0 cm?

An object of mass m with a certain initial speed on a horizontal surface comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the horizontal surface is 0.20, what is the initial speed of the object? Use g = 10 m/s2.

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s². -What is the total energy of the roller coaster at point B?

FIGURE 8-6 A roller coaster of mass 80.0 kg is moving with a speed of 20.0 m/s at position A as shown in Figure 8-6. The vertical height at position A above ground level is 200 m. Neglect friction and use g = 10.0 m/s². -What is the speed of the roller coaster at point B?

An object of mass 20.0 kg is lifted vertically through 1.00 m by a 400 N force. How much work is done by the net force in lifting this object? Use g = 10.0 m/s².

FIGURE 8-5 A 2.0-g bead slides along a wire, as shown in Figure 8-5. At point A, the bead is at rest. Neglect friction and use g = 10 m/s². -Refer to Figure 8-5. What is the speed of the bead at point C?

An object with a mass of 10 kg is moving along a horizontal surface. At a certain point it has a speed of 28 m/s. If the coefficient of friction between the object and the surface is 0.40, how far will the object go before it comes to a stop? Use g = 10 m/s².

What should the height of a slide in a park be so that a child will reach the bottom of the slide with a speed of 15.0 m/s? Use g = 10.0 m/s².

An object of mass m with a certain initial speed on a horizontal surface comes to rest after traveling a distance of 10 m. If the coefficient of kinetic friction between the object and the horizontal surface is 0.20, what is the initial speed of the object? Use g = 10 m/s².