Question

OP
i) Explain about effect of roughness on fictional force
ii) Define lubricant and give some examples​

Answer 1

Answer:

and is

Explanation:

These forces are mainly affected by the "surface texture" and "amount of force" impelling them together. Effect of roughness on frictional force: Choose three surfaces with different levels of roughness. ... This is due to the fact that friction increases with increase in roughness.

2 ans = noun. A substance, such as grease or oil, that reduces friction when applied as a surface coating to moving parts. A slippery liquid, gel, or oil that is used to reduce friction on or soreness of body tissue. One that facilitates conversation or cooperation: saw coffee as a social lubricant.

Answer 2

Answer:

More the roughness and area of contact, more would be the friction.

Explanation:

Frictional force resists motion or tendency of motion. It depends on the roughness of the surface and area of contact. The roughness of any surface  is determined by the hills and valleys which occurs at microscopic level.

The hills and valleys of one surface interlock with the hills and valleys of other surface and resist the motion.

More the roughness and area of contact, more would be the friction. Friction always acts parallel to the surface opposite to the direction of motion.

Coefficient of friction determines how rough a surface is.

So, What is a lubricant ?

A lubricant is a substance, usually organic, introduced to reduce friction between surfaces in mutual contact, which ultimately reduces the heat generated when the surfaces move. It may also have the function of transmitting forces, transporting foreign particles, or heating or cooling the surfaces. The property of reducing friction is known as lubricity.

In addition to industrial applications, lubricants are used for many other purposes. Other uses include cooking (oils and fats in use in frying pans, in baking to prevent food sticking), bio-applications on humans (e.g. lubricants for artificial joints), ultrasound examination, medical examination. It is mainly used to reduce friction and to contribute to a better and efficient functioning of a mechanism.

Common examples of internal lubricants include fatty alcohols, esters (low esterification), and EVA wax. External lubricants provide metal release and help reduce process temperature. Common examples of external lubricants include PE waxes, paraffin, metal soaps, esters (high esterification), amides, and fatty acids.