Uniform rod AB with end B resting against rough vertical wall. Coefficient of friction between wall and rod is μ.

Question

Rod is 2m long and has mass 3kg.

Rod is kept in limiting equilibrium by a light inextensible string, one end of which is attached to the end A of the rod and the other to point C on the wall 2m above B. Angle ABC=120°.

The end B of the rod is about to slip down the wall.

1. By taking moments about C, show that the normal reaction at B is approx. 12.7N.

2. Find the value of μ.

PS: A labelled diagram would be very helpful! Thanks!