Question

A father and son pushed their car to bring it to the side of a road. They had to push with all their might initially. But the push required to keep the car rolling was smaller. Why?

Answer 1

This is because rolling friction is less than sliding friction..... Force required to slide the car much more as compared to the force required to roll down the car on wheels....

Answer 2

Because initially they had to apply force to set the car in motion but once the car started rolling, they had to apply force only to balance rolling friction of the car, the value of which is very less.