A block of mass m rests on truck accelerating at 4 $m/s^2$. Block of mass m is 3m away from end of the truck. If coefficient of friction between block & truck surface is $\mu =0.1$ , the time taken by block to fall off the truck is

 

• A

  $\sqrt{\frac{3}{2}}\mathrm{s}$

• B

  $\sqrt{2}\mathrm{s}$

• C

  1 S

• D

  $\sqrt{6}\mathrm{s}$