Question

Friction is a force which always opposes the motion.Justify

• A. True
• B. False

Answer 1

Answer: (B)

Friction

Friction is defined as the resistance offered by the surfaces that are in contact when they move past each other.

• Friction is a force that is dependent on external factors. Following are the two factors on which friction depends:

1. On the nature of the two surfaces that are in contact

Friction is dependent on the smoothness or roughness of the two surfaces that are in contact with each other. When the surface is smooth, the friction between the two reduces as there is not much interlocking of irregularities. While the surface is rough, friction increases.

2. On the force that is acting on these surfaces

Friction increases when the force is applied along with the irregularities.Friction always acts to oppose any relative motion between surfaces.

• Friction is caused due to the irregularities on the two surfaces in contact. So, when one object moves over the other, these irregularities on the surface get entangled, giving rise to friction. The more the roughness, the more irregularities and more significant will be the friction.

• For example, if a book is resting on a flat table and no force is trying to move the book across the table, so there is no frictional force acting. If we try to slide the book across the table, however, friction will come in to play.