Question

A pool ball rolls up an inclined plane, slows to a stop, and then rolls back down. During this process the magnitude of the acceleration of the pool ball is___________and the velocity is___________. The direction of the acceleration is always _____________. A. Never Zero

B. Not Constant
C. 9.8 m/s/s
D. Down the ramp
E. Up the ramp

Answer 1

A, B and D.

Step-by-step explanation:

The only forces here are the weight (which will have a component perpendicular to the plane and other parallel to it) and the normal. Here the forces perpendicular to the plane (the vertical component of the weight and the normal) cancel out since the ball does not accelerate in that direction, while along the plane we have the parallel component of the weight. This gives is a constant acceleration of value less than g down the ramp, so the possible answers to the first question are A and D.

The velocity is zero when it slows to a stop, not constant, cannot have units of acceleration and is at the beginning up the ramp and at the end down the ramp, so the only possible answer to the second question is B.

Finally, since the direction of the acceleration is down the ramp the only possible answer to the third question is D, making the first answer necessarily A (if we have to chose one answer for each question).