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