Two small rings each of mass ‘m’ are connected to a block of same mass ‘m’ through inextensible light strings. Rings are constrained to move along a smooth horizontal rod. Initially system is held at rest (as shown in figure) with the strings just taut. Length of each string is ‘l’. The system is released from the position shown. Find the speed of the block (v) and speed of the rings (u) when the strings make an angle of theta = 60^(@) with vertical.