Question

A simple pendulum of length `l` has maximum angular displacement `theta` . Then maximum kinetic energy of a bob of mass `m` is
A. `(1)/(2)mgl`
B. `(1)/(2)mglcostheta`
C. `mgl(1-costheta)`
D. `(1)/(2)mglsintheta`

Answer 1

Correct Answer - C
`h=l-lcostheta=(l-costheta)`

`v^(2)=2gh=2gl(1-costheta)=v^(2)_(max)^(2)`
:. `K_(max)=(1)/(2)mv^(2)=mgl(1-costheta)`