A 60 kg body is pushed 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 

Limiting friction 
      $={\mu }_{s}R={\mu }_{s}mg=0.5\times 60\times 10=300N$       
Kinetic friction 
               $={\mu }_{k}R={\mu }_{k}mg=0.4\times 60\times 10=240N$   
Force applied on the body = 300 N and if the body is moving then, net accelerating force
            = Applied force – Kinetic friction 
$\Rightarrow ma=300-240=60\therefore a=\frac{60}{60}=1m/s^2$