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 in the figure . if the cofficient 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 ​

Answer 1

Answer:

As the both the masses are in equilibrium the static friction will be acting on blocks which can be found from balancing the forces in vertical direction.

The FBD of block A

Writing force balance in vertical direction for block A

f

1

= weight of the block A =20 N

Writing force balance in vertical direction for block B

f

2

−f

1

= weight of the block B 100 N

The value of frictional force between wall and block B is 120 N

Answer 2

Answer:

The frictional force applied by the wall in block B is 120N

Explanation:

central idea in vertical direction, weights are balanced by frictional forces.

Consider FBD of block A and B as shown in diagram above .

As the blocks are in equiblrium, balance forces are in horizantal and vertical direction .

For the system blocks A + B

F = N

for block A , FA = 20N and for blocks B

FB = FA + 100 = 20+100 = 120N