Question

Consider the situation shown in the figure. The wall is smooth but the surfaces of blocks $A$ and $B$ in contact are rough. The friction on $A$ due to $B$ in equilibrium

• A. Is upward
• B. Is downward
• C. Is zero
• D. The system cannot remain in equilibrium for any value of $\text{F}$

Answer 1

Answer: (A)

Is upward

Answer 2

Block 'A' cannot be in equilibrium. Due to F sin ? component (upwards) on block 'B', Block 'A' moves downwards relative to block 'B'. So, friction on block 'B' downwords.