A rod of length l = 1 m resting on a wall and the floor. Its lower end A is pulled towards right with a constant velocity v = 2 m/s. Find the angular velocity of the rod  when it makes an angle θ=60∘ with the vertical.

As rod is a rigid body, the distance between point A and point B should remain unchanged. Hence the relative velocity of ends of rod along its length should be zero.It means the velocities of ends of rod along its length must be equal.vAsin⁡θ=vBcos⁡θ⇒vB=vAsin⁡θcos⁡θ=vtan⁡θor vB=vAtan⁡θ=vtan⁡θ             …(i)Then, ωBA=vBAl=vBA⊥l=vAcos⁡θ−−vBsin⁡θl⇒ ωBA=vAcos⁡θ+vBsin⁡θl            …(ii)Using Eqs. (i) and (ii), ωBA=vlcos⁡θ=21×cos⁡60∘=4m/sThis is also angular velocity of rigid body about centre of mass.