Question

Consider the system shown in figure. The wall is smooth, but the surfaces of blocks $\text{A}$ and $\text{B}$ in contact are rough. The friction on $\text{B}$ due to $\text{A}$ in equilibrium is

• A. Upward
• B. Downward
• C. Zero
• D. The system cannot remain in equilibrium

Answer 1

Answer: (D)

Considering $\text{A}$ and $\text{B}$ as a system. There is no vertical force in upward direction to support their weight. Therefore, the system cannot remain in equilibrium.