AP Physics - Chapter 8 Practice Test

Multiple Choice
Identify the choice that best completes the statement or answers the question.

____ 1. A single conservative force F
x
= (6.0x 12) N (x is in m) acts on a particle moving along the x axis. The
potential energy associated with this force is assigned a value of +20 J at x = 0. What is the potential energy at
x = 3.0 m?
a. +11 J
b. +29 J
c. +9.0 J
d. 9.0 J
e. +20 J

____ 2. A 12-kg block on a horizontal frictionless surface is attached to a light spring (force constant = 0.80 kN/m).
The block is initially at rest at its equilibrium position when a force (magnitude P = 80 N) acting parallel to
the surface is applied to the block, as shown. What is the speed of the block when it is 13 cm from its
equilibrium position?



a. 0.78 m/s
b. 0.81 m/s
c. 0.71 m/s
d. 0.58 m/s
e. 0.64 m/s

____ 3. A 0.60-kg object is suspended from the ceiling at the end of a 2.0-m string. When pulled to the side and
released, it has a speed of 4.0 m/s at the lowest point of its path. What maximum angle does the string make
with the vertical as the object swings up?
a. 61
b. 54
c. 69
d. 77
e. 47

____ 4. A 2.5-kg object suspended from the ceiling by a string that has a length of 2.5 m is released from rest with the
string 40 below the horizontal position. What is the tension in the string at the instant when the object passes
through its lowest position?
a. 11 N
b. 25 N
c. 42 N
d. 18 N
e. 32 N

____ 5. A 0.04-kg ball is thrown from the top of a 30-m tall building (point A) at an unknown angle above the
horizontal. As shown in the figure, the ball attains a maximum height of 10 m above the top of the building
before striking the ground at point B. If air resistance is negligible, what is the value of the kinetic energy of
the ball at B minus the kinetic energy of the ball at A (K
B
K
A
)?



a. 12 J
b. 12 J
c. 20 J
d. 20 J
e. 32 J

____ 6. A skier weighing 0.70 kN goes over a frictionless circular hill as shown. If the skier's speed at point A is 9.2
m/s, what is his speed at the top of the hill (point B)?



a. 3.1 m/s
b. 6.2 m/s
c. 5.2 m/s
d. 4.1 m/s
e. 6.5 m/s

____ 7. A spring (k = 200 N/m) is suspended with its upper end supported from a ceiling. With the spring hanging in
its equilibrium configuration, an object (mass = 2.0 kg) is attached to the lower end and released from rest.
What is the speed of the object after it has fallen 4.0 cm?
a. 90 cm/s
b. 79 cm/s
c. 96 cm/s
d. 83 cm/s
e. 57 cm/s

____ 8. A 2.0-kg block sliding on a horizontal frictionless surface is attached to one end of a horizontal spring (k =
200 N/m) which has its other end fixed. If the block has a speed of 4.0 m/s as it passes through the
equilibrium position, what is its speed when it is 20 cm from the equilibrium position?
a. 2.6 m/s
b. 3.1 m/s
c. 3.5 m/s
d. 1.9 m/s
e. 2.3 m/s

____ 9. A 20-kg mass is fastened to a light spring (k = 380 N/m) that passes over a pulley as shown. The pulley is
frictionless, and the mass is released from rest when the spring is unstretched. After the mass has dropped
0.40 m, what is its speed?



a. 2.2 m/s
b. 2.5 m/s
c. 1.9 m/s
d. 1.5 m/s
e. 3.6 m/s

____ 10. A spring (k = 600 N/m) is placed in a vertical position with its lower end supported by a horizontal surface. A
2.0-kg block that is initially 0.40 m above the upper end of the spring is dropped from rest onto the spring.
What is the kinetic energy of the block at the instant it has fallen 0.50 m (compressing the spring 0.10 m)?
a. 5.3 J
b. 6.8 J
c. 6.3 J
d. 5.8 J
e. 6.5 J

____ 11. A 3.0-kg mass is dropped from the edge of a 50-m tall building with an initial speed of zero. The mass strikes
the ground with a downward velocity of 25 m/s. How much work is done on the mass by air resistance
between the point where it is dropped and the point where it strikes the ground?
a. 0.46 kJ
b. 0.53 kJ
c. 0.61 kJ
d. 0.38 kJ
e. 0.81 kJ

____ 12. A large spring is used to stop the cars after they come down the last hill of a roller coaster. The cars start at
rest at the top of the hill and are caught by a mechanism at the instant their velocities at the bottom are zero.
Compare the compression of the spring, x
A
, for a fully loaded car with that, x
B
, for a lightly loaded car when
m
A
= 2m
B
.



a.
x
A
= x
B
.
b. x
A
= x
B
.
c.
x
A
= x
B
.
d. x
A
= 2 x
B
.
e. x
A
= 4 x
B
.

____ 13. Cubical blocks of mass m and side l are piled up in a vertical column. The total gravitational potential energy
of a column of three blocks is
a.
mgl.
b. 3mgl.
c.
mgl.
d. 6mgl.
e. 9mgl.

____ 14. A spring with spring constant k = 800 N/m is extended 12 cm from its equilibrium position. A spring with 6.0
cm extension from equilibrium will have the same potential energy as the first spring if its spring constant is
a. 200 N/m.
b. 400 N/m.
c. 800 N/m.
d. 1600 N/m.
e. 3200 N/m.

____ 15. The block shown is released from rest when the spring is stretched a distance d. If k = 50 N/m, m = 0.50 kg, d
= 10 cm, and the coefficient of kinetic friction between the block and the horizontal surface is equal to 0.25,
determine the speed of the block when it first passes through the position for which the spring is unstretched.



a. 92 cm/s
b. 61 cm/s
c. 71 cm/s
d. 82 cm/s
e. 53 cm/s

____ 16. A 1.2-kg mass is projected down a rough circular track (radius = 2.0 m) as shown. The speed of the mass at
point A is 3.2 m/s, and at point B, it is 6.0 m/s. How much work is done on the mass between A and B by the
force of friction?



a. 8.9 J
b. 7.3 J
c. 8.1 J
d. 6.6 J
e. 24 J

____ 17. The two masses in the figure are released from rest. After the 3.0-kg mass has fallen 1.5 m, it is moving with
a speed of 3.8 m/s. How much work is done during this time interval by the frictional force on the 2.0 kg
mass?



a. 12 J
b. 17 J
c. 20 J
d. 8.0 J
e. 28 J

____ 18. A pendulum bob has potential energy U
0
when held taut in a horizontal position. The bob falls until it is 30
away from the horizontal position, when it has potential energy U
A
. It continues to fall until the string is
vertical, when it has potential energy U
B
. Compare its potential energies at O, A, and B.



a. U
0
= U
A
= U
B
.
b. U
A
U
B
= 2U
0
.
c. U
A
U
B
= U
0
U
A
.
d. U
0
= U
B
= 2U
A
.
e. U
0
U
A
= 2(U
A
U
B
).

____ 19. Which of the following is a conservative force? (All refer to a car on a slope.)
a. The force you exert on the car pushing it uphill.
b. The force exerted by rain drops falling on the car.
c. The frictional force of the road on the car.
d. The gravitational force acting on the car.
e. The force you exert on the car (pushing it uphill) after it starts to slide downhill.

Problem

20. A simple pendulum, 2.0 m in length, is released from rest when the support string is at an angle of 25 from
the vertical. What is the speed of the suspended mass at the bottom of the swing?
AP Physics - Chapter 8 Practice Test
Answer Section

MULTIPLE CHOICE

1. ANS: B PTS: 1

2. ANS: A PTS: 1

3. ANS: B PTS: 1

4. ANS: C PTS: 1

5. ANS: A PTS: 1

6. ANS: C PTS: 1

7. ANS: B PTS: 1

8. ANS: C PTS: 1

9. ANS: A PTS: 1

10. ANS: B PTS: 1

11. ANS: B PTS: 1

12. ANS: C PTS: 1

13. ANS: C PTS: 1

14. ANS: E PTS: 1

15. ANS: C PTS: 1

16. ANS: C PTS: 1

17. ANS: D PTS: 1

18. ANS: C PTS: 1

19. ANS: D PTS: 1

PROBLEM

20. ANS:
1.9 m/s

PTS: 1