Question

what is a mean position of pendulam

Answer 1

The position from pendulum start moving is called mean position.

Answer 2

If by “simple pendulum in the mean position at rest” you are speaking of simply a hanging bob, a stationary pendulum-like device that has not been activated yet, it has no kinetic energy in the laboratory frame of reference. But its potential energy can be whatever you like.

Define mean position and extreme position with reference to a simple pendulum. ... Mean position is the position of the bob when the freely suspended pendulum is at rest.