Define

(i) static friction

(ii) sliding friction and

(iii) rolling friction.

(i) Static friction: The maximum opposing force between the object and the surface in contact with it, so long as the object remains stationary even on applying the external force, is called the static friction.

(ii) Sliding friction: When the body begins to slide on a surface, the force exerted by the surface on the object is called the sliding friction.

(iii) Rolling friction: When an object rolls over a surface, the force which opposes the rolling motion of the object is called the rolling friction.