Question

What happens to the coefficient of friction, when weight of the body is doubled ?

Answer 1

Hint:Coefficient of Friction (COF) shows us the amount of friction which exists between two surfaces. Weight of the body is defined as the force exerted by an object and mass can be defined as the amount of matter in an object.

Complete step by step answer:
Coefficient of friction is the ratio of the frictional force which is resisting the motion of the two surfaces that are in contact with each other to the normal force that presses the two surfaces together. Coefficient of friction is generally symbolized by μ (pronounced as mu). It is as Greek letter.

The coefficient of friction mainly depends on the surfaces like the nature of the material and roughness of the surface. Therefore, it will not change if the weight is doubled.On the other hand, when the weight of the body is doubled then there will be no change in the coefficient of friction because the frictional force is directly proportional to the normal reaction.
Friction ∝ Normal
$F\alpha N \\
\Rightarrow F=\mu N(F=\mu mg) \\
\Rightarrow \mu =\frac{F}{N}$
where, $F$=frictional Force, $N$=Normal Force, $μ$=coefficient of friction, $m$=mass of the body and $g$=acceleration due to gravity.

Coefficient of friction of dimensionless means it has no units. So, when weight of the body is doubled then frictional force and normal reaction will also get doubled as they are directly proportional to each other and the coefficient of friction will remain constant.

Note:The coefficient of friction is a number which is the ratio of the resistance friction force divided by the normal or perpendicular force(N) pushing the objects together.The Friction Coefficient tells us the minimum force needed for an object to slide on a surface, divided by the forces pressing them. Less force is required to slide/drag/slip when the coefficient of friction is low but when the coefficient of friction is high then more force is required for sliding to occur.