A rock, tied at the end of a rope, is swirled in a vertical circle (the rock's speed changes during the motion). The work done on the rock by the tension in the rope
A) is positive.
B) is zero.
C) is negative.
D) changes from positive to negative and back as the velocity of the rock changes its direction.
E) depends on the weight of the rock.

Question

Quizplus · Accepted Answer

The tension in the rope acts perpendicular to the direction of the rock's instantaneous velocity at any point in the circle, so it does no work on the rock.

A Rock, Tied at the End of a Rope, Is