Solution

Friction : • The force of friction always acts in a direction opposite to that in which the body tends to move, which means against the direction of the force. • 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. • The force of friction depends upon the roughness/smoothness of the surfaces. • The force of friction is independent of the area of contact between the two surfaces. • If objects start moving and there is no friction the object can never stop.