One end of a spring of natural length
2m and spring constant
k=100N/m is fixed at the ground and the other is fitted with a smooth ring of mass
1kg which is allowed to slide on a horizontal rod fixed at a height
2m (fig.) initially, then spring makes an angle of
37o with the vertical when the system is released from rest. Find the speed (in m/s) of the ring when the spring becomes vertical.