The figure an `L` shaped body of mass `M` placed on smooth horizontal surface. The block `A` is connected to the body by means of an inexiensible string , which is passing over a smooth pulley of negligible mass.Another block `B` of mass `m` is placed against a vertical wall of the body. Find the minimum value of the mass of block `A` so that `B` remain stationary relative to the wall. Coefficient of friction between the block `B` and the vertical wall is `mu`.

Explanation

`a = (m_(A) g)/(m_(A) + M + m)`
For the equilibrium of `B`
`mg = mu N = mu (ma) = (mu mm_(A) g)/(m_(A) + M + m)`
`:. m_(A) = ((M + m) m)/((mu - 1) m)`
` m_(A) =((M + m))/(mu -1)`