WORK Work (W) is the product of force and displacement.
It is a scalar quantity with an SI unit of joule (J). 1 J is the amount of work done when a force of 1 N is applied over a distance of 1 m. 1 J 1 N m
No work is done without motion
The term ‘work’ has a different meaning in physics than in the everyday use of the word. In physics the term ‘work’ means the transfer of energy into or out of a system.
If you apply a force on an object and there’s no movement, then no work is being done ‘on’ the object. Although you would expend energy and get tired, the energy of the object is not changing; therefore, no work is done on the object.Typically, the phrase ‘on the object’ is left out and we simply say ‘no work is done’.
SAMPLE PROBLEM 5A A person pushed a car a distance of 15 m with a force of 500 N. Calculate the work done by the person.
SAMPLE ANSWER 5A
Using the formula for work, making sure all values are in their standard unit: W Fs (500)(15) 7 500 Work done is 7 500 J.
