Question

X. Answer in detail,
1. Friction is a necessary evil - Explain.
2. Give the different types of friction and
explain each with an example.
3. Describe an experiment to prove that
friction depends on the nature of a surface.
4. Explain how friction can be minimised.
5. Describe an experiment to prove that the
pressure in a liquid increases with depth.​

Answer 1

1)Frictional force causes a lot of losses in general upkeep and wear and tear of machinery. ... But almost all crucial tasks cannot be carried out without the presence of friction. Basic activities like walking and writing on a surface are possible due to friction. Hence it is considered as a necessary evil .

2)Friction is the force that opposes motion between any surfaces that are in contact. There are four types of friction: static, sliding, rolling, and fluid friction. Static, sliding, and rolling friction occur between solid surfaces. Fluid friction occurs in liquids and gases.

3)Take a sheet of paper, a handkerchief, a hand towel, a rectangular piece of glass and wood as surfaces and a pencil. 2 Now roll the pencil on each surface. 3 Number the surfaces in the order in which the pencil rolled easily on them. Also, mention whether the surface is rough or smooth.

4)The interlocking of irregularities on the surfaces of two bodies in contact, which cause friction, is overcome to a great extent by the use of lubricants like oil, grease, etc. Friction between the sliding surfaces of two objects can be reduced by making the surfaces in contact smooth by polishing them.

5)The bulging out of rubber sheet tied to the glass tube fixed in the wall of plastic bottle demonstrates that water present in plastic bottle exerts pressure on the walls of the bottle. ... 1)The pressure exerted by a liquid on the walls of container increases with increasing depth.

hope this help you!!!!