PRACTICE MULTIPLE CHOICE FOR EXAM 4 (CH’s 7,8,9)

1. Does the centripetal force acting on an object do work on the object?

A. Yes, since a force acts and the object moves, and work is force times distance.

B. Yes, since it takes energy to turn an object.

C. No, because the object has constant speed.

D. No, because the force and the displacement of the object are perpendicular.

2. Two children ride on a merry-go-round that is rotating at a uniform rate. One

child sits on the edge of the merry-go-round while the other sits halfway to the

center.

A. They will both have the same linear speed, but their angular velocities will differ.

B. They will have different linear speeds and different angular velocities.

C. They will have different linear speeds, but the same angular velocity.

D. They will both have the same linear speed and the same angular velocity.

3. 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. the side the boy is sitting on will tilt downward

B. the side the girl is sitting on will tilt downward

C. nothing, the seesaw will still be balanced

D. it is impossible to say without knowing the masses and the distances involved

4. The pressure difference between the top and bottom of an airplane wing in flight which

results from the difference in the flow of air across each surface is explained by

A. Archimedes Principle

B. Bernoulli’s Principle

C. Pascal’s Principle

D. Newton’ 3^rd law

5. A submarine rests on the sea bottom. The normal force exerted up on the sub by the sea

floor is equal to

A. the weight of the sub

B. the weight of the water displaced by the sub

C. the weight of the sub plus the weight of the water displaced by the sub

D. the weight of the sub minus the weight of the water displaced by the sub

ANSWERS:

1. D

2. C

3. C

4. B

5. D