Rotational 2

A rod OA of mass m and length L hinged at end O can rotate smoothly in vertical plane about horzontal axis passing through O .It is released from a horizontal position as shown. and strikes a block of mass M kept vertically below at distance L on a smooth horizontal surface.The block after collisin moves on the smooth vertical circular track of diameter L such that the force exerted by the circular track on the block at C is one third of its wieght .If the rod after collision rotates through an angle 30 degrees frm horizontal . find the ratio of masses M/m