Translations of Encyclopedia about Physics

Work, Output, Energy

These concepts are often confused between each other and wrongly interpreted. In any case, major differences exist between them. The word energy is derived from the Greek word energie, which expresses an acting force. Energy is often defined as the ability for an object to execute work.

Classical physics differentiates between two types of energy: kinetic energy (the energy of moving bodies) and potential energy (positional energy). While the kinetic energy of an object is proportional to its mass and weight, its potential energy is defined by its position or coordinates within a force field of another object. Modern physics has discovered an equivalence between mass and energy (Albert Einstein), so mass is considered as one form of energy.

There are three types of potential energy: potential gravitational energy (given the position of an object relating to another object exerting a gravitational force on it), electromagnetic energy (relating to the position of an object within an electromagnetic field), and potential atomic energy (which results from various strong, mutually acting elementary particles).

In different areas of physics and when examining technical goals, different forms of energy are referred to, such as heat energy, chemical energy, nuclear energy and so on. However, each of these forms of energy could be transformed into any one of their other basic forms.

For example, the heat energy of a certain object may be transferred into the molecular movement within it. If we increase the temperature of the object, we are also increasing the average speed in which the molecules within it are moving - meaning they contain more energy.

The concept of energy plays a major role in physics, given by the fact that all forms of energy may be converted to their basic forms and by the fact that, according to the law of maintaining energy, the energy contained within any given system can be neither destroyed nor created, where the energy is always only transformed.

The specific unit of energy is the joule (J) or, as it is primarily in technical practice, kilowatt-hours (kWh).

In physics, work is not understood as a certain work act, such as cutting word, but rather as the expenditure of force along a certain path. Work is executed when some object is forced to move due to some force acting on it. Executing work essentially means that one form of energy is converted into another, such as the chemical energy present in gasoline converted into the kinetic energy of an automobile.

Output (P) is work which is or may be executed within a certain amount of time. It is the share of executed work and the time necessary for the output. In other terms, output is the speed at which work is executed. This speed may be set as a constant value within a defined time period, or may be calculated as an immediate value.

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