A small disc can slide in a circular path on a frictionless inclined plane inclined at an angle of `30^(@)` with the help of a thread as shown. Mass of the disc is `m` and acceleration due to gravity is `g`. If the disc is released, when the thread is horizontal, expression for the tension in the thread at the lowest point is

Options

A. `(1)/(2)mg`
B. `(3)/(2)mg`
C. `2mg`
D. `3mg`

Answer

B

Explanation

Applying work energy theorem from initial to final position, `mg sin30^(@)l=(1)/(2)mv^(2)`
Applying NLM, along radial direction at final position `-mgsin30^(@)+T=(mv^(2))/(l)rArrT=(3)/(2)mg`