Question

A block of mass $4\text{kg}$ is kept on a rough horizontal surface. The coefficient of static friction is $0.8$. If a force of $19\text{N}$ is applied on the block parallel to the floor, then the force of friction between the block and the floor is

• A. $32\text{N}$
• B. $18\text{N}$
• C. $19\text{N}$
• D. $9.8\text{N}$

Answer 1

The correct option is C $19\text{N}$

Given,
Mass of block $\left(m\right)=4\text{kg}$
Coefficient of static friction $\left(\mu \right)=0.8$
Applied force $\left(F\right)=19\text{N}$
Now, limiting friction $(f_s{)}_{\text{max}}={\mu }_{s}N={\mu }_{s}mg$
$=0.8\times 4\times 10=32\text{N}$
Since, applied force is less than the limiting friction.
So, force of friction, $f=19\text{N}$