Question

What is the value of the force F to be applied horizontally on a block of mass 5 kg which is in contact with a wall as shown in the figure. (take g = 10 m/s²) such that it does not fall down. The coefficient of friction between the block and the wall is 0.4.
(A) 200 N
(B) 20 N
(C) 12.5 N
(D) 125 N

Answer 1

Answer: Option D. 125N

Explanation:

Please check the attached pic for the solution

Answer 2

Answer:

Option (D) is correct.

Explanation:

Since block is rested  along the wall so, it exerts a downward force weight due to the earth gravity.So,

$F= mg$

F = 5 x 10 = 50 N..................(1)

Since when a horizontal force is applied then force of friction acts on the body.So,

Force of friction $F = \mu R = 0.4\times R$.................(2)

Using (1) and (2) we get,

R = 125 N

So, option (D) is correct.