Question

A minimum horizontal force of $10N$ is necessary to just hold a block stationary against a wall. The coefficient of friction between the block and the wall is $0.2$. The weight of the block is:-

• A. $100N$
• B. $50N$
• C. $20N$
• D. $2N$

Answer 1

The correct option is D $2N$

Given
The reaction force, $N=10N$
Coefficient of friction $\mu =0.2$
The weight of block is
$W=mg$
Also, $F=mg$
$\Rightarrow W=F$...............(1)
where, m is mass of the block and g is acceleration due to gravity.
Now, the force due to friction is
$F=\mu N$ .................(2)
From (1) and (2) we get and as block is stationary
$W=\mu N$
$W=\left(0.2\right)\left(10\right)$
$W=2N$