Write the displacement variable in simple pendulum and the propagation of light.

There is a simple pendulum hanging from the ceiling of a lift. When the lift is stand still, the time period of the pendulum is $T$. If the resultant acceleration becomes $g/4,$ then the new time period of the pendulum is

What happens to the time period of a simple pendulum when it is taken to moon's surface from earth's surface ?

A simple pendulum is hanging from a peg inserted in a vertical wall. Its bob is stretched in horizontal position from the wall and is left free to move. The bob hits on the wall the coefficient of restitution is $\frac{2}{{\sqrt 5 }}$. After how many collisions the amplitude of vibration will become less than $60°$

A simple pendulum executing $S.H.M.$ is falling freely along with the support. Then