Question

A bucket is whirled in a vertical circle with a string attached to it.The water in bucket does not fall down even when the bucket is inverted at the top of its path. In this position choose most appropiate option.

• A. $mg=\frac{m{v}^2}{r}$
• B. mg is greater than $\frac{m{v}^2}{r}$
• C. mg is not greater than $\frac{m{v}^2}{r}$
• D. mg is not less than $\frac{m{v}^2}{r}$

Answer 1

Answer: (C)

mg is not greater than $\frac{m{v}^2}{r}$

Arm exerts a force to turn the bucket - which is the centripetal force. a centrifugal force acts on the rotating body which pins the water to the bucket( quite like in a car). now if the centrifugal force is greater than the force of gravity. your water will remain in the bucket when it's above your head.
The force created by the circular swinging motion mimics that of gravity, which is what keeps the water in the bucket in the first place.