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 coeffcient of friction between the box and the surface below it is 0.15. On a straight road, the truck starts from rest and accelerates with `2 m s^-2`. At what distance from the starting point does the box fall off the truck? (Ignore the size of the box).