Question

Consider a system of two blocks $A,B$ and the wall. The wall is smooth but the surface of $A$ and $B$ in contact are rough. If force $F$ is exerted on $B$ as shown, Then:

• A. the friction on $B$ due to $A$ in equilibrium is upwards
• B. the friction on $B$ due to $A$ in equilibrium is downwards
• C. the friction on $B$ due to $A$ is zero
• D. the system cannot remain in equilibrium

Answer 1

The correct option is D the system cannot remain in equilibrium

Here, as the wall is smooth , so, because of smooth surface of wall the system can't remain in equilibrium. Also, both the blocks will feel acceleration due to gravity downwards.

so, D is correct.