Question

Given in the figure are two blocks $A$ and $B$ of weight $20N$ and $100N$ respectively. These are being pressed against a wall by a force $F$ as shown. If the coefficient of friction between the blocks is $0.1$ and between block $B$ and the wall is $0.15$, the frictional force applied by the wall on block $B$ is:

• A. $80N$
• B. $120N$
• C. $150N$
• D. $100N$

Answer 1

Answer: (B)

$120N$

Normal force on block $A$ due to $B$ and between $B$ and wall will be $F$
Friction on $A$ due to $B=20N$
Friction on $B$ due to wall $=100+20=120N$