Question

A simple pendulum, suspended from the coiling of a lift, has a period of oscillation T, when the lift is at rest. If the lift starts moving upwards with an acceleration a =3g, then the new period will be
A. T/2
B. 2T
C. T/3
D. 3T

Answer 1

Correct Answer - A
The period of pendulum when lift is stationary
`T=2pisqrt((L)/(g))`
When the lift is moving upwards, the acceleration of the lift increases.
`therefore T_(1)=2pisqrt((L)/(g+a))=2pisqrt((L)/(g+3g))=2pisqrt((L)/(4g))`
`(T_(1))/(T)=sqrt((g)/(4g))=(1)/(2) therefore T_(1)=(T)/(2)`