Question

A 60 kg body is pushed horizonatally With just enough force to start it moving across a floor and the same force continues to act afterwards. The coefficient of static friction and sliding friction are 0.5 and 0.4 respectively. The acceleration of the body is

• A. $6m/s^2$
• B. $4.9m/s^2$
• C. $3.92m/s^2$
• D. $1m/s^2$

Answer 1

The correct option is D $1m/s^2$

the maximum static friction that can act on the body $F=\mu mg=0.5\times 60\times 10=300N$
since the force is just 300N the body will translate and the type of friction will be kinetic instead of static.
hence the net acceleration is $F-\mu mg=ma$
$a=\frac{F-\mu mg}{m}=\frac{300-0.4\times 60\times 10}{60}=1m{s}^{-2}$