Figure shows two block `A` and `B` pushed against the wall with the force `F` . The wall is smooth but the surfaces in contact of `A` and `B` are rough. Which of the following is true for the system of blocks to be at rest againts wall?

Options

A. `F` should be equal to weight of `A` and `B`
B. `F` should be less than weight of `A` and `B`
C. `F` should be more than weight of `A` and `B`
D. System connot be in rquilibrium (at rest).

Answer

D

Explanation

For system `A` and `B` together there is no upward force to balance the weight `(m_(A)+m_(B))g` . So, system can never be in equilibrium.