In the pulley arrangement shown in Fig the pulley `p_(2)` is movable .Assuming the coefficient of friction between `m` and surface to be `mu` the minimum value of `M` for which `m` is at rest is

Options

A. `M = (mu m)/(2)`
B. `m = (mu M)/(2)`
C. `M = (m)/(2mu)`
D. `m = (M)/(2 mu)`

Answer

a

Explanation

`f = 2T`
and `T = Mg`
If m be at rest friction will be static
`f le mu N`
`2Mg le mu mg rArr M =(mu g)/(2)`