Question

Write one solid lubricant and liquid lubricant.

Answer 1

Hint To answer this question we have to analyse the role of lubricants in day-to-day life. Connecting from these applications, we will get the required examples. Lubrication is used to reduce friction. It is generally used for moving machine parts.

Complete step by step answer
The lubricants are the substances which are used to reduce the friction which acts between two surfaces in contact, between which relative motion can occur. As the friction acts along the interface between two surfaces, so the lubricants are applied there only. Hence they help to keep the parts smoothly moving. By reducing the friction, they basically reduce the loss of energy in the form of heat. As the energy losses are prevented, the overall efficiency of a machine is increased.
The lubricants are classified, on the basis of their molecular structure, as the solid and the liquid lubricants.
The solid lubricants are in the powdered form. They are also known as dry lubricants. An example of the solid lubricants is Graphite.
The liquid lubricants are composed of different kinds of base oil and some additives. An example of the liquid lubricants is mineral oil.

Note
The solid lubricants are inserted between the bearing surfaces. They are used in very extreme conditions. They are used in the anti-friction linings, metallic films, in suspensions etc. The example of graphite given above is used in air compressors, ball bearings, track joints etc.
The liquid lubricants are used in the conditions of high speed and load size. They are used in different components of the automobiles, for example, in the chassis, in the suspension system, in the transmission system etc.