Energy Definition and Examples

Energy Definition and Examples Energy is defined as the capacity of a physical system to perform work. However, its important to keep in mind that just because energy exists, that doesnt mean  its necessarily available to do work. Forms of Energy Energy exists in several forms such as heat, kinetic or mechanical energy, light, potential energy, and electrical energy. Heat s are energy released by fission and fusion. Other forms of energy may include geothermal energy and classification of energy as renewable or nonrenewable. There may be overlap between forms of energy and an object invariably possesses more than one type at a time. For example, a swinging pendulum has both kinetic and potential energy, thermal energy, and (depending on its composition) may have electrical and magnetic energy. Law of Conservation of Energy According to the law of conservation of energy, the total energy of a system remains constant, though energy may transform into another form. Two billiard balls colliding, for example, may come to rest, with the resulting energy becoming sound and perhaps a bit of heat at the point of collision. When the balls are in motion, they have kinetic energy. Whether they are in motion or stationary, they also have potential energy because they are on a table above the ground. Energy cannot be created, nor destroyed, but it can change forms and is also related to mass. The mass-energy equivalence theory states an object at rest in a frame of reference has a rest energy. If additional energy is supplied to the object, it actually increases that objects mass. For example, if you heat a steel bearing (adding thermal energy), you very slightly increase its mass. Units of Energy The SI unit of energy is the joule (J) or newton-meter (N * m). The joule is also the SI unit of work.