Question

Q12.) (a.) What are the factors that affect the force of friction? (1)
(b.) Mention any two ways by which we can increase friction? (1)​

Answer 1

Factors affecting force of friction : -

• Friction depends partly on the smoothness of the contacting surfaces, a greater force being needed to move two surfaces past one another if they are rough than if they are smooth.

• However, friction decreases with smoothness only to a degree; friction actually increases between two extremely smooth surfaces because of increased attractive electrostatic forces between their atoms.

• Friction does not depend on the amount of surface area in contact between the moving bodies or (within certain limits) on the relative speed of the bodies.

• It does, however, depend on the magnitude of the forces holding the bodies together. When a body is moving over a horizontal surface, it presses down against the surface with a force equal to its weight, i.e., to the pull of gravity upon it; an increase in the weight of the body causes an increase in the amount of resistance offered to the relative motion of the surfaces in contact.

Methods to increase friction : -

• To increase friction, the surfaces in contact have to be made rough.

• The two surfaces in contact can also be pressed harder to increase force between them or by increasing the mass of the object resting on the surface.
• Use of adhesive materials that stick surfaces , also increases friction between them.