Question

If the mass of the object is doubled then what will be the effect of time period of the compound pendulum?

(a) Doubled

(b) Remains same

(c) Halved

(d) Decreases by √2 times

This question was posed to me in a job interview.

Question is taken from Compound Pendulum in chapter Simple Harmonic Motion of Machine Kinematics

Answer 1

Right choice is (d) Decreases by √2 times

The explanation is: The time period of a compound pendulum is given by:

(2π)\(\sqrt{(\frac{I}{mgl})}\), now the dependency of the time period on the mass is inversely proportional to the root of mass, hence it decreases by √2 times.