# Work And Energy

Topics: Energy, Potential energy, Joule Pages: 4 (840 words) Published: December 16, 2014
﻿Summary

When a force displaces, work is said to be done. The force should be the net force and there should be a net displacement of the object.

Work done by force acting on an object in the direction of the force is equal to the product of the magnitude of the force and the displacement covered by the object  in the direction of the force.

The work done is measured in joule in the SI system after the scientist James Prescott Joule. Erg is the CGS unit of work.

Conditions for work to be done:
A net force should act on an object.
The object must be displaced in the direction of the net force.
Work is said to be done when an object is displaced on applying a certain force. W = F × s, Where
W = Work done on an object
F = Net force on the object
s = Displacement of the object
Joule is defined as the work done when the net force of one newton acts on a body and displaces it in the direction of the force by one metre.
Work done could be either positive or negative.

When both the force and the displacement are in the same direction, positive work is done.
When force acts in a direction opposite to the direction of displacement, the work done is negative. Summary

LearnNext Video
The energy of an object is its ability to do work. Energy is the cause and work is its effect. Therefore both work and energy have the same units, which is joule (J) in the SI system and erg in the CGS system. Energy is also a scalar quantity. Energy exists in many forms.

Examples
Mechanical energy which is either in the form of potential energy or kinetic energy or a combination of the both, electrical energy, light energy, thermal energy, nuclear energy and sound energy etc. Potential energy is the energy possessed by a body by virtue of its position or state. It is further classified into gravitational potential energy (GPE) and elastic potential energy (EPE). GPE is by virtue of height of a body from a reference level,...