A rod of mass m and length L, lying horizontally, is free to rotate about a vertical axis through its centre, A horizontal force of constant magnitude F acts on the rod at a distance of L/4 from the centre. The force is always perpendicular to the rod. Find the angle rotated by the rod during the time t after the motion starts.
The angle of rotation of the rod is 
Given
The mass of the rod is given as “m” and length of the rod is given as “L”, the force acting on the rod is “F”, at a distance of L/4 from the center.
Formula Used
The formula used is that of a torque which tells us the mechanics of force which helps the object to rotate. The formula is
and
where
F is the force applied on the object; r is the radius of the object turning. Turning angle is given by 
, I is the moment of Inertia, L is the length at which the force is applied.
Explanation
The mass of rod is given as “m” and length “L”. So the torque acting on the rod is
The moment of Inertia is given as
Now finding the angle of rotation
in terms of angular acceleration
we get:
Finding, the angle of rotation in term of angular length
is
