A simple pendulum is released from A as shown. If m and l represent the mass of the bob and length of the pendulum, the gain in kinetic energy at B is

Options

A. `(mgl)/(2)`
B. `(mgl)/(sqrt(2))`
C. `(sqrt(3))/(2)mgl`
D. `(2)/(sqrt(3))mgl`

Answer

C

Explanation

Loss of potential energy is coming from A to
`B=mgh=mglcos30^(@)`
`=(sqrt(3))/(2)mgl`

Kinetic energy gained = loss of potential energy
`=(sqrt(3))/(2)mgl`