Question

A $60kg$ mass is pushed with a enough force to start it moving and the same force is continued to act afterward. If the coefficient of static friction and sliding friction are $0.5$ and $0.4$ respectively, then the acceleration of the body will be

• A. $1m{s}^{-2}$
• B. $3.9m{s}^{-2}$
• C. $4.9m{s}^{-2}$
• D. $6m{s}^{-2}$

Answer 1

The correct option is A $1m{s}^{-2}$

Kinetic friction
$={\mu }_{k}R={\mu }_{k}mg=0.4\times 60\times 10=240N$
and the limiting friction
$={\mu }_{S}R={\mu }_{S}mg=0.5\times 60\times 10=300N$
So, the force applied on the body is $300N$ and if the body is moving afterwards with the same force, then
Net accelerating force
$=$ Applied force $-$ Kinetic force
$ma=300-240$
$a=\frac{60}{m}=\frac{60}{60}=1m{s}^{-2}$.