This question has been bugging me for ages.... I can't seem to draw the diagram correctly.

A light inextensible string of length 3 metres is threaded through a smooth vertical ring which is free to turn. The spring carries a particle at each end. One particle, P, of mass m is at rest at a distance of 1 metre below the ring, while the other particle B of mass M is rotating in a horizontal circle whose centre is P.

Show that the velocity, v, of B in terms of m, and M is given by: