The Properties of Energy
- Energy can be transferred from one object to another.
- Energy comes in many different forms, which can generally be divided into Potential or Kinetic energy.
- Energy can be converted from any one of these forms into any other, and vice versa.
- Energy is never created or destroyed - this is called the First Law of Thermodynamics.
Light or Electromagnetic Energy:
The energy transmitted to the Earth from the Sun as light is also called "electromagnetic radiation", and may be thought of as a pure form of energy in the form of little packets of energy called photons. This word derives from the word "photo", which means "light".
Heat or Thermal energy:
The energy radiated to Earth from the sun is called thermal or heat energy and is the same energy form as boiling water. For example, boiling water possesses "thermal energy", which is the collective, kinetic and potential energy of the vibrating molecules in the water.
There is potential energy contained inside things which can be released as heat or other forms of energy when combusted with oxygen. The energy in fossil fuels is chemical energy, which releases heat energy when burnt. Food energy such as glucose (blood sugar) in your body also possesses "chemical energy" because the glucose releases energy to your body when chemically reacted (combusted) with oxygen.
"Nuclear reactions" are the source of energy within the Sun, the core of our Earth and nuclear reactors. The similarity is that the reactions occurring involve changes in the structure of the nuclei of atoms.
With both nuclear fusion and fission some of the matter making up the nuclei is actually converted into energy. In other words matter itself is a form of energy!
This is described by E=mc2.
The energy stored in a piece of matter at rest equals its mass times the speed of light squared.