Work done by a frictional force is (Consider all possibilities) – (a) Negative (b) Positive (c) Zero (d) All of the above

By BYJU'S Exam Prep

Updated on: September 25th, 2023

Work done by a frictional force is negative, positive, and zero. When the body is really moved a short distance in the direction of the force applied, the force is said to have performed work. The ability to perform tasks is referred to as energy. As a result of the body being displaced in the direction of force, the force’s effort in moving the body a distance s is written as:

  • W = F . s
  • W = Fs cos θ

As a result, the amount of work that a force does is equal to the dot or scalar product of the force and the body’s displacement. Static friction occurs when a body is at rest and a force called static frictional force is exerted. Kinetic Frictional Force is the name given to friction that opposes the motion of a body in motion.

Frictional Force

Case 1:

Motion is resisted when an object is moving across a rough surface by kinetic frictional forces.

kinetic frictional forces

In this instance, the frictional force opposes the applied force and is hence antithetical to the displacement. so that the frictional force and displacement have an angle of 180°.

W = Fs cos 180° = Fs cos (90° + 90°)

W = – Fs sin 90° = -Fs

Frictional forces provide negative work.

Case 2:

When an object is placed on a rough surface and is subjected to a force, it will not move until the static frictional force has been overcome.

There is no displacement in this instance, s = 0

W = Fs cos θ = F(0) cos θ = 0

In this instance, a frictional force produces no work.


If two blocks are placed stacked on top of one another and force is applied to the bottom block, the higher block will move in the direction of the applied force.

The higher block is moving as a result of frictional force.

The task completed is thus positive in this instance.

Frictional forces

Therefore, the work produced by friction can be positive, negative, or zero.


Work done by a frictional force is (Consider all possibilities) – (a)Negative (b)Positive (c)Zero (d)All of the above

Frictional forces produce negative, positive, and zero amounts of work. The force is considered to have done work when the body actually moves a small distance in the direction of the applied force.

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