Question

Given in the figure are two blocks A and B of weight $20N$ and $100N$ respectively. The blocks 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

The correct option is B $120N$

FBD of block A,

$f_1=W_A=20N$
FBD of block B,

$f_2=f_1+W_B$
$=20+100$
$=120N$
The correct option is (B)