Question

if you push a heavy box which is rest,you must exert some force to start its motion howewer the box is sliding you apply a lesser force to maintain that motion why

Answer 1

All objects that posses mass possess inertia( it is the reluctance of an object to start or stop moving) thus when the box was at rest it needed an external force to make it moving , as it slides down the potential energy that the box had was converted to kinetic energy and that why it doesn't need much force to slide provided the surface is smooth.

Hope it helps u.

Answer 2

why because when you push the box it will be in motion. when the object is in motion it get energy to move that energy is called kinetic energy