Question

Figure (8-E14) shows a light rod of length I rigidly attached to a small heavy block at one end and a hook at the other end. The system is released from rest with the rod in a horizontal position. There is a fixed smooth ring at a depth h below the initial position of the hook and the hook gets into the ring as it reaches there. What should be the minimum value of h so that the block moves in a complete circle about the ring ?

Answer 1

The minimum velocity required to cross the height point $c=\sqrt{2}gl$

Let the rod released from a height h.

Total energy at A= total energy at B

$mgh=\frac{1}{2}m{v}^2$

$mgh=\frac{1}{2}m\left(2gl\right)$

[Because v is the required velocity at B such that the block makes a complete circle. Refer Q=49]

So, $h=l$