1 Laws of friction
Laws of friction:
- The force of friction always acts in direction opposite to that in which body tends to move.
- Till the limiting value is reached, the magnitude of friction is exactly equal to the force which tends to move the body.
- The magnitude of the limiting friction bears a constant ratio to the normal reaction between the two surfaces of contact and this ratio is called coefficient of friction.
- The force of friction depends upon the roughness/smoothness of the surfaces.
- The force of friction independent of the area of contact between the two surfaces.
- After the body starts moving, the dynamic friction comes into play, the magnitude of which is less than that of limiting friction and it bears a constant ratio with normal forces. This ratio is called coefficient of dynamic friction.