The time period of a simple pendulum in a lift descending with constant acceleration g is

Options

(a) T=2π√l/g
(b) T=2π√l/2g
(c) zero
(d) Infinite

Correct Answer:

Infinite

Explanation:

When the lift falls freely under gravity, effective ‘g’ for pendulum in the lift = zero.
T = 2π √(l/g) = 2π√(l/o) = Infinite.