Question

Mention the methods used to decrease friction.

Answer 1

Hint: We know that frictional force is resistive force. It always acts in the opposite direction as that of the motion as a result there is energy loss in the process. This happens due to the various imperfections present between two bodies. In order to reduce friction, we need to reduce these imperfections.

Complete answer:
 As friction as a resistive force, it acts when two bodies (surfaces) come in contact and as soon as these bodies slide over each other. Friction opposes the motion of one body over another. This happens as the surface of any body is not smooth, it is uneven at microscopic level. This leads to some jerk in the motion as when the body starts to slide, some instantaneous force is needed to overcome the resistance of frictional force. As a result, some energy is lost in this process.

Methods used to decrease friction:
-When we polish surfaces, this reduces the uneven surfaces to a greater extent.
-For objects that move in fluids such as planes and boats, their shape can be streamlined in order to reduce the frictional force between the surfaces.
-Using lubricants, such as oil or grease. It reduces the friction between the surfaces.
-For objects which are rolling, ball bearings are used to reduce the friction.

Note: Friction is very harmful when the system is of large components. For systems with large components, the number of contact surfaces is large and hence more energy is lost. To lubricate them, more cost is involved. The above-mentioned methods are useful and very important.