Question

What is the nature of the work done by frictional force?

Answer 1

Hint: In order to deal with this question first we will define the frictional force, further we will derive its equation, then according to the definition and the equation of force we will comment upon the nature of frictional force and the work done by these forces.

Complete step by step answer:

Formula used- $W = F.s$
Frictional force refers to the force produced by the touch and slipping of two surfaces against each other.
As we all know:
Frictional force is often in contrast to the body's motion. And frictional force against body movement is applied.
As the formula for the work done by any force is given as:

$W = F.s$

Since the direction of force and the displacement suffered by the body is in opposite direction,
So work done:

$
  W = F.s \\
   \Rightarrow W = Fs\cos \theta \\
 $

Work done becomes negative.
In some cases when frictional force opposes the motion of the body and the body does not move in those cases work done by frictional force is zero and in all other cases when there is a motion of the body in the opposite direction to the force applied.
The work done by force of friction is negative.
Hence, the nature of the work done by frictional force is either zero or negative.

Note- A few influences can affect the frictional force: (1) These forces are primarily affected by the structure of the surface and by the amount of energy that impels them together. (2) The object's angle and location influence the sum of frictional force. Friction has lots of importance in our day to day life in walking, writing, driving and many more.