Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown in figure. 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 in block B is

Question

Given in the figure are two blocks A and B of weight 20 N and 100 N, respectively. These are being pressed against a wall by a force F as shown in figure. 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 in block B is (A) 100 N (B) 120 N (C) 80 N (D) 150 N

Tardigrade Admin · Accepted Answer

Note It is not given in the question, best assuming that both blocks are in equilibrium. The free body diagram of two blocks is as shown below,

Reaction force

R =

applied force

F

For vertical equilibrium of

A

;

f_{1} =

friction between two blocks

= W_{A} = 20 N

For vertical equilibrium of

B

;

f_{2} =

friction between block

B

and wall

= W_{B} + f_{1}

= 100 + 20

= 120 N