Question

A block of mass $5\text{kg}$ is on a rough horizontal surface at rest. Now a force($F$) of $24\text{N}$ is imparted to it with negligible impulse. If the coefficient of kinetic friction is $0.4$ and $g=9.8{\text{m/s}}^2$, then the acceleration of the block is

• A. $0.26{\text{m/s}}^2$
• B. $0.39{\text{m/s}}^2$
• C. $0.69{\text{m/s}}^2$
• D. $0.88{\text{m/s}}^2$

Answer 1

The correct option is D $0.88{\text{m/s}}^2$

By the FBD of the block,
the frictional force $\left(f_k\right)$ is acting towards left , $f_k=\mu N=0.4\times 5\times 9.8=19.6\text{N}$
Using $\sum F=ma$
$24-f_k=ma$

$24-19.6=5a$

$a=0.88m/s^2$

Hence option D is the correct answer