A smooth ring A of mass m can slide on a fixed horizontal rod. A string tied to the ring passes over a fixed pulley B and carries a block C of mass `M(=2m)` as shown in figure. At an instant the string between the ring and the pulley makes an angle `theta` with the rod. (a). Show that, if the ring slides with a speed v, the block descends with speed `v cos theta`, (b). With what acceleration will the ring starts moving if the system is released from rest with `theta= 30^0`
