A semicircular ring of radius R is fixed on a smooth horizontal table. A small block is projected with speed u so as to enter the ring at end A. Initial velocity of the block is along tangent to the ring at A and it moves on the table remaining in contact with the inner wall of the ring. The coefficient of friction between the block and the ring is `mu`.
(a) Find the time after which the block will exit the ring at B.
(b) With what speed will the block leave the ring at B.

Answer

(a) `t = (R)/(muu) [e^(pimu) - 1]`
(b) ` V = (u)/(e^(pimu))`