A small ring of mass 0.2 kg is threaded on a fixed vertical rod. The end A of a light inextensible string is attached to the ring. The other end C of the string is attached to a fixed point of the rod above A. A horizontal force of magnitude 8 N is applied to the point B of the string, where AB = 1.5 m and BC = 2 m. The system is in equilibrium with the string taut and AB at right angles to BC (see diagram).

1. Find the tension in the part AB of the string and the tension in the part BC of the string.
2. The equilibrium is limiting with the ring on the point of sliding up the rod. Find the coefficient of friction between the ring and the rod.