Rotational Motion

A thin uniform \(\operatorname{rod} A B\) of mass \(m\) and length \(l\) is hinged at one end \(A\) to the ground level. Initially the rod stands vertically and is allowed to fall freely to the ground in the vertical plane. The angular velocity of the rod when its end \(B\) strikes the ground is ( \(g=\) acceleration due to gravity)