Work and Energy



Tanusri Gururaj, Academic content writer of Physics at Edumarz

To understand the scientific definition of work, let us take a few examples:

  1. A person reads a book and writes notes. 

Work not done.

  1. A person pushes a heavy box but it does not move.

Work not done. 

  1. A person pushes a heavy box and it gets displaced. 

Work is done.

  1. A person lifts a book.

Work is done.

The above examples show that for work to be done, two conditions are necessary:

  1. Force

  2. Displacement 

  • Work is defined as the product of force acting on a body and displacement.

W = F x s

Where W is the work done

F is the force acting on the object

s is the displacement of the object

  • SI unit of work = N m or Joule (J)

1 Joule (J) can be defined as the amount of work done when a force of 1 newton (N) displaces the body by 1 metre (m)  along the line of action of force.

  • Work is positive when the displacement is in the direction of force and negative when displacement and force are in opposite directions.

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