Laws of Limiting and Kinetic Friction

Laws of Limiting Friction 

1. The direction of force of friction is always in a way that it opposes the direction of motion. 

2. It depends upon the roughness/smoothness of the surfaces in contact and acts tangentially to the interface between them. 

3. It is independent of area and shape of surfaces in contact as long as the normal reaction remains the same.

4. It is directly proportional to normal reaction 'R' between the two surfaces in contact.

Laws of Kinetic Friction

1. The direction of kinetic friction is such that it always opposes direction of motion.

2. It remains constant even if the body is accelerated.

3. It also does not depend upon the area of the surface in contact only nature.