Question

In a seconds pendulum, mass of bob is 30 gm. If it is replaced by 90 gm mass. Then its time period will [Orissa PMT 2001]
A) 1 sec B) 2 sec C) 4 sec D) 3 sec

Answer 1

A seconds pendulum is a pendulum whose period is precisely two seconds; one second for a swing in one direction and one second for the return swing, a frequency of 1/2 Hz

It can be shown by calcuiation that in earth where g = 9.81 m/sec²

the length of the seconds pendulum is = 1 metre.

Hence replacement of the bob of mass 30g by a bob of 90g will not change the Time period,it will remain same as before i.e. 2s