Question

what is the force of friction?How is it useful

Answer 1

Whenever an object moves against another object, it feels frictional forces. These forces act in the opposite direction to the movement. Friction makes it harder for things to move.

Friction can be useful:

friction between our shoes and the floor stop us from slipping

friction between tyres and the road stop cars from skidding

friction between the brakes and wheel help bikes and cars slow down

Frictional forces are much smaller on smooth surfaces than on rough surfaces, which is why we slide on ice.