Question

A ball tied at the end of a perfect string tied tightly (assume fixed) to a wooden bar at the other end is rotating with constant angular velocity. Its tangential velocity will _______

(a) Increase with time

(b) Decrease with time

(c) Will remain constant

(d) Will decrease exponentially

I had been asked this question at a job interview.

Question is from Non-Uniform Circular Motion in portion Laws of Motion of Physics – Class 11

Answer 1

Right choice is (b) Decrease with time

For explanation I would say: As the other end of the string is fixed to the wooden bar, the motion will cause the string to wrap itself around the bar. This will result in decrease in the effective radius of the circular motion. Tangential velocity v = ωr, the tangential velocity will decrease with time.