A thin rod of mass `m` and length `2L` is made to rotate about an axis passing through its center and perpendicular to it. If its angular velocity changes from `O` to `omega` in time `t`, the torque acting on it is

Options

A. `(m l^(2)omega)/(l^(2)t)`
B. `(m l^(2)omega)/(3 t)`
C. `(m l^(2)omega)/(t)`
D. `(4 ml^(2)omega)/(3 t)`

Answer

B

Explanation

`t = I a = (m4 l^(2))/(12)(omega)/(t)=(m l^(2)omega)/(3t)`.