Download Test Review Problems

Test Review Problems
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
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1. When an object is moving with uniform circular motion, the object’s tangential speed
a. is circular.
b. is perpendicular to the plane of motion.
c. is constant.
d. is directed toward the center of motion.
2. When an object is moving with uniform circular motion, the centripetal acceleration of the object
a. is circular.
b. is perpendicular to the plane of motion.
c. is zero.
d. is directed toward the center of motion.
3. What is the term for the net force directed toward the center of an object’s circular path?
a. circular force
c. centripetal force
b. centrifugal force
d. orbital force
4. The centripetal force on an object in circular motion is
a. in the same direction as the tangential speed.
b. in the direction opposite the tangential speed.
c. in the same direction as the centripetal acceleration.
d. in the direction opposite the centripetal acceleration.
5. When a car makes a sharp left turn, what causes the passengers to move toward the right side of the car?
a. centripetal acceleration
c. centrifugal force
b. centripetal force
d. inertia
6. Which of the following quantities measures the ability of a force to rotate or accelerate an object around an axis?
a. axis of rotation
c. tangential force
b. lever arm
d. torque
7. Where should a force be applied on a lever arm to produce the most torque?
a. closest to the axis of rotation
b. farthest from the axis of rotation
c. in the middle of the lever arm
d. It doesn’t matter where the force is applied.
8. Suppose a doorknob is placed at the center of a door. Compared with a door whose knob is located at the edge,
what amount of force must be applied to this door to produce the torque exerted on the other door?
a. one-half as much
c. one-fourth as much
b. two times as much
d. four times as much
9. Which has more rotational inertia, a bicycle wheel or a solid disk of the same mass and diameter?
a. The wheel.
b. The disk.
c. They both have the same rotational inertia.
10. A person's rotational inertia is least about _____.
a. an axis through the person's feet
b. the person's median axis
c. the person's longitudinal axis
d. an axis through the person's hands
e. the person's transverse axis
11. Angular momentum is defined as _____.
a. momentum times rotational velocity
b. mass times velocity
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c. rotational inertia times linear velocity
d. none of the above
Two people sit on a balanced seesaw. When one person leans toward the center of the seesaw, that person's end
of the seesaw will _____.
a. fall
b. rise
c. stay at the same level
A 3-kg ball is whirled on the end of a string that is 2 m long. The ball's linear speed is 4 m/s. What is its angular
momentum?
a. 2 kg·m·m/s
b. 6 kg·m·m/s
c. 8 kg·m·m/s
d. 24 kg·m·m/s
e. 48 kg·m·m/s
When you carry a heavy load with one arm, why do you tend to hold your free arm away from your body?
a. To change the mass of your body
b. To be ready to grab something in case you fall
c. To look good
d. To change the center of gravity of your body and the load
e. To change the weight of your body and the load
If you try to touch your toes while standing flat against a wall, you probably will fall over. The reason this
happens is that
a. your center of gravity is not located directly above your support area.
b. your center of gravity is outside your support area.
c. both A and B
When an ice skater pulls in his hands to turn faster _____.
a. angular momentum must be conserved
b. his moment of inertia changes
c. his rotational speed changes
d. all of the above
Short Answer
17. Explain how an object moving at a constant speed can have a nonzero acceleration.
18. What provides the centripetal force for a car driving on a circular track?
19. Is there an outward force in circular motion? Explain.
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SHORT ANSWER
17. ANS:
Acceleration depends on the change in an object’s velocity. An object moving at a constant speed can
experience a nonzero acceleration if the direction of the object’s motion changes.
DIF: II
OBJ: 7-1.1
18. ANS:
Friction between the car’s tires and the track provides the centripetal force.
DIF: II
OBJ: 7-1.2
19. ANS:
No, there is only an inward force causing a deviation from a straight-line path. The tendency to move in a
straight line away from the circular path is inertia.
DIF: II
OBJ: 7-1.3
SHORT ANSWER
17. ANS:
Acceleration depends on the change in an object’s velocity. An object moving at a constant speed can
experience a nonzero acceleration if the direction of the object’s motion changes.
18. ANS:
Friction between the car’s tires and the track provides the centripetal force.
19. ANS:
No, there is only an inward force causing a deviation from a straight-line path. The tendency to move in a
straight line away from the circular path is inertia.