Question

A block of mass $2\text{kg}$ is placed on the floor. The coefficient of static friction is $0.4$. If a force of $2.8\text{N}$ is applied on the block parallel to the floor, the force of friction between the block and floor is (take $g=10{\text{ms}}^{-2}$)

• A. $2.8\text{N}$
• B. $8\text{N}$
• C. $2\text{N}$
• D. $\text{zero}$

Answer 1

The correct option is A $2.8\text{N}$

$f_{\text{max}}=\mu mg=0.4\times 2\times 10=8\text{N}$
Since the applied force is less than $f_{\text{max}}$ so block will remain at rest. Force of friction will be equal to the applied force which is $2.8\text{N}$.