The rear side of a truck is open and a box of 40 kg mass is placed 5 m away from the open end as shown in Fig 5.22 . The coffecient of friction between the box and the surface below it is 0.15 . On a straight road, the truck starts from rest and acceleration with `2 ms^(-2)` . At what distance from the starting point does the box fall off the truck ? ( Ignore the size of the box ).