A rock is suspended from a string; and it moves downward at constant speed. Which one of the following statements is true concerning the tension in the string if air resistance is not ignored?
A)The tension is zero newtons.
B)The tension points downward.
C)The tension is equal to the weight of the rock.
D)The tension is less than the weight of the rock.
E)The tension is greater than the weight of the rock.

Question

Quizplus · Accepted Answer

The tension is less than the weight of the rock because air resistance acts upward, reducing the net force needed to maintain constant speed.

A Rock Is Suspended from a String; and It Moves