Get A+ with YaClass!
Register now to understand any school subject with ease and get great results on your exams!


In the previous section, we have discussed several activities that we usually consider as work in day-to-day life.
For each of these activities, think of the following questions and try to answer them:
  1. What is the work being done on?
  2. What is happening to the object?
  3. Who (what) is doing the work?
Example 1 - Carrying a box
In most cases, carrying a box is not considered work. The force and distance you apply must be in the same direction for something to be recognised as work,  
In the case of carrying a box, you are using a vertical force to lift a box while you are moving horizontally in the distance. This indicates zero work is being done as the force and distance are not applied in the same direction.
Example 2 - A book falls off a table (free falls to the ground)
This is an example of work. There is a force (gravity) that acts on the book, which causes it to be displaced in a downward direction (i.e., "fall").
Example 3 - A man applies a force on a wall and gets exhausted
This is not an example of work. The wall is not displaced. A force must cause a displacement 'for the work to be done'.
Example 4 -  A servant carries a plate full of meals above his head by one arm straight across the room at a uniform speed
This is not an example of work. In this case, there is a force (the plate is pushed up by the servant) in upwards, and there is a displacement (the plate is moved horizontally across the room) in the horizontal direction. Yet, the force does not cause displacement. To cause a displacement, there must be a component of force in the direction of the displacement.
Example 5 -  A rocket accelerates through space
This is an example of work. A force (the expelled gases push on the rocket) causes the rocket to be displaced through the space.