Question

1. If you push a heavy box which is at rest, you must exert some force to start its
motion. However once the box is sliding you apply a lesser force to maintain that
motion. Why?​

Answer 1

Heavy box which is at rest posses Static friction.

And sliding box posses sliding friction.

We know that Static friction is always more than the sliding friction.

Static friction>sliding friction>rolling friction.

Therefore in order to move a box at rest we have to overcome static friction and we have to apply more force.