## Energy facts

1)The word energy comes from the Greek word energeia.
2)Most types of energy are either a form of kinetic energy or potential energy.
3)Common examples include heat energy, elastic potential energy, chemical energy, sound energy, nuclear energy, geothermal energy , gravitational potential energy and electric Potential energy
4) Kinetic energy refers to the energy an object has because of its movement. A Truck in motion has kinetic energy, as does a basketball when you pass or shoot it.

## Use of concept of electric potential

We already know about electric field and electric potential. We also know that electrostatic field is completely characterized by vector function E(r). The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding. Now a question arises why do we need introduction of electric potential when we already have electric field for the description of electric force between charges.

## What is heat?

1)The mean energy transferred between the two system as a result of pure thermal interaction is called Heat.It is the transfer of energy from the higher temperature object to a lower temperature object.

2) The total amount of energy transferred as heat is conventionally written as Q for algebraic purposes. Heat released by a system into its surroundings is by convention a negative quantity (Q < 0); when a system absorbs heat from its surroundings, it is positive (Q > 0).

3) Heat is similar to work as both represent ways of transferring the energy.