Two block A and B placed on a plane surface as shown in the figure. The mass of block A is `100 kg` and that B is `200 kg`. Block A is tied to a stead and blcok B is pulled by a force F. If the coefficient of friction between the surfaces of A and B is `0.2` and the coefficient of friction between B and the plane is `0.3` then for for the motion of B the minimum value of F will be -
.

Explanation

When B is tries to move, by applying a force F, then the fricitional forces acting on the blokc B are `f_(1)` and `f_(2)` with limiting values, `f_(1)=(mu_(s))_(A)m_(A)g` and `l_(2)=(mu_(s))_(B)(m_(A)+m_(B))g`
Then minimum value of F should be (for just tending to move),
`F=f_(1)+f_(2)=0.2xx100g+0.3xx300g=110g=1100N`