CCommunity
Laws of Static friction:
(1) The force of friction always acts in a direction opposite to that in which the body tends to move.
(2) Till the limiting value is reached, the magnitude of friction is exactly equal to the force which tends to move the body.
(3) The magnitude of the limiting friction bears a constant ratio to the normal reaction between the two surfaces.
(4) The force of friction depends upon the roughness/smoothness of the surfaces.
(5) the force of friction is independent of the area of contact between the two surfaces.
(6) It does not depend upon the relative velocity between them
After the body starts moving, the kinematic friction comes into play.
Law of kinematic friction: For moderate speeds, the force of friction remains constant. But it decreases slightly with the increase of speed.