The SI unit of work is Joule (J). For example, if a force of 5 newtons is applied to an object and moves 2 meters, the work done will be 10 newton-meter or 10 Joule. It should be noted that 1 J = 1 N ⋅ m = 1 kg ⋅ m2/s2.
Example of Work
An object is horizontally dragged across the surface by a 100 N force acting parallel to the surface. Find out the amount of work done by the force in moving the object through a distance of 8 m.
Solution:
Given:
F = 100 N, d = 8 m
Since F and d are in the same direction, θ = 0, [θ is the angle of the force to the direction of movement], therefore
W = FdCos θ
W = 100 x 8 x Cos 0
W = 800 J [Since Cos 0 = 1]