Question

A hollow spherical pendulum is filled with mercury has time period T. If mercury is thrown out completely, then the new time period ___________

(a) Increases

(b) Decreases

(c) Remains the same

(d) First increases and then decreases

This question was posed to me during an interview.

This question is from Wave Motion in portion Waves of Engineering Physics I

Answer 1

Right answer is (c) Remains the same

To explain I would say: Position of centre of gravity remains unaffected when mercury is thrown out. Hence effective length and time period remain the same.