Answer:
A force that opposes the relative motion of two objects in contact and sliding past each other.
Explanation:
Friction occurs due to roughness, roughness, or slight surface bumps when two (or more) surfaces are in contact with each other. According to Newton's laws when we push (or pull) an object, it does not move. This is because on this object there is a resistance that the bodies in contact offer to the movement. This counter force is called the friction force F = µ.N (µ coefficient of friction).
That is, for Newton, friction occurs when a force that opposes the relative movement of two objects in contact and sliding one after another.
