A pendulum is oscillating on either side of its rest position. The correct statement is

1. It has only the kinetic energy at its each position.
2. It has maximum kinetic energy at its extreme position.
3. It has the maximum potential energy at its mean position.
4. The sum of its kinetic energy and potential energy remain constant throughout the motion.

The sum of its kinetic and potential energy remains constant throughout the motion.

Reason — The kinetic energy decreases and the potential energy becomes maximum at B.

After a moment the the to and fro movement starts again.

So, from B to A, again the potential energy changes into kinetic energy and this process repeat again and again.

So, when the bob in its state of to and from movement it has potential energy at the extreme position B or C and kinetic energy at resting position A.

It has both the kinetic energy and potential energy at an intermediate position.

Hence, the sum of kinetic and potential energy remain same at every point of movement.