Friction:
Friction: Friction is a force which oppose the motion.
Work of friction:
(i) It opposes the motion.
(ii) It opposes intention of motion.
The force of friction is applicable at the point of contact between two surfaces, and in the direction of common tangent.
Type of friction:
(i) Statics Friction: No relative motion between two bodies in contact.
Direction is opposite to the intention of motion.
(a) Self-adjusting
(b) Limiting
(ii) Kinetic Friction:
(a) Sliding Friction
(b) Rolling Friction
Amount of friction depents on its roughness or smotheness of surfaces.