Two blocks of mass `m_(1) = 6 kg` and `m_(2) = 3kg` are as shown in the diagram. Coefficient of friction between `m_(1)` and `m_(2)` and between `m_(1)` and `m_(2)` and between `m_(1)` and the surface is `0.5` and `0.4` , respectively . The maximum horizontal force that can be applied to the mass `m_(1)` so that they move without separation is

Options

A. `41 N`
B. `61 N`
C. `81 N`
D. `101 N`

Answer

C

Explanation

`0.4 xx 30 = 3a rArr a = 4 m//s^(2)`
`F - 12 - 45 = 6a = 60 xx 4 = 24`
`F = 81 N`