Question

A horizontal force of $10\text{N}$ 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. $2\text{N}$
• B. $20\text{N}$
• C. $50\text{N}$
• D. $100\text{N}$

Answer 1

The correct option is A $2\text{N}$

Given horizontal force $F=10\text{N}$ and coefficient of friction between block and wall $\left(\mu \right)=0.2$.
We know that at equilibrium the horizontal force provides the normal reaction to the block against the wall.
Therefore, the normal reaction to the block $\left(R\right)=F=10\text{N}$
We also know that weight of the block $\left(W\right)=$ Frictional force
$=\mu R=0.2\times 10=2\text{N}$
Hence, the correct answer is option (a).