Question

When a stone tied to a string is whirled in a circle, the work done on it by the string is:

• A. Positive
• B. Negative
• C. Zero
• D. Undefined

Answer 1

The correct option is C

Zero

The force that is acting on the ball is the 'centripetal force'. This force is directed to the centre of the string and is always perpendicular to the direction of motion. As centripetal force is perpendicular to the direction of motion, the work done by it will be zero.