Common Forms of Energy
There are two possible forms of energy in physics, kinetic energy and potential energy. In common usage, however, this is expanded to many possible forms of energy. Some of the more common forms are described here.
Kinetic Energy is the energy that any moving object has by virtue of its motion. The kinetic energy of a moving object is one half of its mass times the square of its velocity (K.E. = (1/2)mV2).
Image Credit: Alistair Craven
Potential Energy is stored energy that has the potential to do work or be converted to another form. An object that can move downward under the force of gravity has gravitational potential energy. Also, a compressed spring and a stretched rubber band have potential energy, because they can do work as they move back to their natural position.
Thermal Energy, commonly simply called heat, is the energy of any object with a temperature above absolute zero, due to the kinetic energy of its molecules. For a given quantity of material, the higher its temperature, the more thermal energy it has.
Chemical Energy is a particular form of potential energy. It is the energy stored in a chemical that can be released by some reaction of that chemical. An example is the chemical energy in coal that is converted to thermal energy when the coal is oxidized (burned).
Electrical Energy is energy that is made available due to the flow of an electrical current through a conductor. Electrical energy is actually energy in transit. For example, it is converted to heat when electrical current passes through a resistor, or it is converted to kinetic energy when electrical current passes through the windings of an electrical motor, causing the motor to turn.
Mechanical Energy is a term used to refer to the sum of the kinetic energy and potential energy of a system.