Topic: Engineering Mechanics
A stone of mass m at the end of a string of length l is whirled in a vertical circle at a constant speed. The tension in the string will be maximum when the stone is-
- A. At the top of the circle
- B. Half-way down from the top
- C. Quarter-was down from the top
- D. At the bottom of the circle
Answer: D. At the bottom of the circle
Explanation: At the bottom, the tension in the string will be maximum because of both weight of stone and centrifugal force acting in downward direction. $T_{bottom} = mg + mr\omega^{2}$ (maximum). At the top, $T_{top} = mr\omega^{2} - mg$ (minimum).