A pendulum is executing simple harmonic motion and its maximum kinetic energy is `K_(1)`. If the length of the pendulum is doubled and it perfoms simple harmonuc motion with the same amplitude as in the first case, its maximum kinetic energy is `K_(2)` Then:

Explanation

Maximum kinetic energy at lowest point B=Change in
potential energy
i.e. `K= mgl(1-cos theta)`
where `theta=` angular amp.

`K_(1)=mgl(1- cos theta)`……………I
`K_(2)=mg(2l)(1-cos theta)`………....ii
Solving i and ii we get
`K_(2)=2K_(1)`