Energy

Energy is defined as the capacity of a body for doing work. The SI unit of energy is the joule. 1 joule is the work done by a force of 1 newton moving a distance of 1 metre in the direction of the force.

All forms of energy fall into two categories, potential and kinetic energy. We can organise different forms of energy within these two categories.

Potential Energy

Stored energy and energy of position.

1. Chemical Energy
- stored in the bonds of atoms and molecules - coal, petrol, biomass.
2. Gravitational Potential Energy
- the energy of place or position.
3. Nuclear Energy
- energy stored in the nucleas of an atom.
4. Stored Mechanical Energy
- stored in objects through the application of force - springs.

Kinetic Energy

This is motion, motion of atoms, molecules, objects or waves.

1. Electrical Energy
- movement of electrons.
2. Motion
- movement of objects.
3. Radiant Energy
- electromagnetic energy - light, x-rays, gamma rays and radio waves.
4. Sound
- movement of energy through substances in longitudinal waves.
5. Thermal Energy
- the internal energy in substances - the vibration of atoms and molecules within substances.

See also: Calorie, Conservation of Energy, Efficiency, Energy Balance, First Law of Thermodynamics, Gravitational Potential Energy, Joule, Kinetic Energy, Renewable Energy, Therm, Work.