What is energy?

Energy is an abstract property that describes the ability to perform work or cause changes. The energy principle states that energy cannot arise from nothing or disappear, only transform from one form to another.

Different forms of energy

The two fundamental forms of energy are kinetic energy and potential energy. In principle, all forms of energy can be classified as kinetic energy or potential energy, or a combination of both.

Kinetic energy

Energy associated with motion. The faster something moves, the heavier it is, and the more kinetic energy it has. An example of this is a moving car.

Potential energy

Energy stored in an object due to what it is or what it is capable of doing. Two different forms of potential energy are:

1. Gravitational potential energy
   For example: a ball lifted above ground level. The higher the ball is lifted, the more potential energy it has due to gravity.
2. Elastic potential energy
   For example: a stretched elastic or compressed spring. When a spring is stretched or compressed, it has potential energy. When you release the spring, the energy will be released.

Some other forms of energy are:

Thermal energy

Thermal energy is the internal energy of a system, and it relates to the movement of the particles that make up a substance. The faster the particles move, the higher the temperature and thus the thermal energy.

Electrical energy

Energy transferred by the movement of electric charges through a conductor.

Chemical energy

Energy stored in chemical compounds and released through chemical reactions.

Light energy

Energy transported through electromagnetic waves. Sunlight is an example of light energy.