A block of mass `m` lying on a rough horizontal surface of friction coefficient `mu` is pulled by a force `F` as shown , the limiting friction between the block and surface will be

Options

A. `mu mg`
B. `mu(mg + (F)/(2))`
C. `mu(mg - (F)/(2))`
D. `mu(mg - (sqrt(3) F)/(2))`

Answer

C

Explanation

`uarr : N + F sin 30^(@) = mg rArrr N = mg - F sin 30^(@)`
`= mg - (F)/(2)`
`f_(lim) = f_(max) = mu N = mu (mg - (F)/(2))`