A person ties a rock to a string and whirls it around in a vertical circle such that sometimes the rock is going straight upward and sometimes the rock is going straight down.She whirls the rock at the minimum speed (constant in time)such that the string is always taut (no sag).When is the tension the highest?
A)It is highest when the rock is at the lowest elevation.
B)It is highest when the rock is at the highest elevation.
C)The tension is constant as the rock moves around in a circle.

Question

Quizplus · Accepted Answer

The tension is highest when the rock is at the lowest elevation because, at this point, the gravitational force and the centripetal force both act in the same direction, increasing the tension in the string.

A Person Ties a Rock to a String and Whirls