a pendulum of the length L is suspended from the ceiling of an elevator. When the elevator is at rest , the period of the pendulum is T. In instant when the pendulum reaches its highest position the elevator starts the free fall. What is the period of the pendulum if the elevator is freely falling?

If the elevator is falling, the pendulum is falling, so it is not oscillating.

so what?

For other viewers who didn't understand like Ray.. Since its not oscillating there is no period, therefore it is 0.

No oscillation means that the period is infinity. If the period were zero, the pendulum would be moving with infinite velocity.

0 second

the time period would be infinte. t=sqrt(1/g-a) a=9.8

0 s