A block `A` of mass `200 kg` rest on a block `B` of mass `300 kg`. `A` is tied with a horizontal string to a wall. Coefficient of friction between `A` and `B is 0.25` and that between `B` and floor is `0.2`. The horizontal force `F` needed to move the block `B` is

Options

A. `550 N`
B. `1100 N`
C. `1500 N`
D. `2200 N`

Answer

C

Explanation

`f_(1) =0.25 xx 2000 = 500 N`
`f_(2) = 0.2 (200 + 300) xx 10 = 1000 N`
`F = f_(1) + f_(2) = 1500 N`