A block of mass `2 kg` is placed on a truck as shown in the figure. The coefficient of friction between the block and surface is `0.5`. The truck starts from the rest and moves with acceleration `a_(0)`. (a) Find the friction force acting on the block if (i) `a_(0) = 2 m//s^(2)` , (ii) `4 m//s^(2)` , (iii) `6 m//s^(2)` and (b) if acceleration of truck `a_(0) = 8 m//s^(2)`. After how much time the blocks falls off the truck and the distance travelled by the truck in this time.