Types of Energy

The word energy has an everyday meaning and a scientific one.
The everyday meaning is force, vigor, power, strength, action skills, or determination, decision in everything you do.

Definition of Energy
At the actual level of knowledge and technical development, it is considered that the Universe which surrounds us exists under two forms: substance and force. Substance is characterized by two fundamental aspects: mass and energy. Mass is the measure of inertia and gravitation, and energy is the scalar measure of substance movement. The word energy is well known, but the concrete content of the notion is not so popular or rigorously analyzed, because of some subtle particularities, characteristic to certain forms of energy. The most general definition presents energy as measure of substance movement. This definition is correct, but it is not very clear, as substance is characterized by more forms of movement.

Energy
Energy is the measure of a physical system. It defines the quality of the changes and processes which take place in the Universe, beginning with movement and finishing with thinking. The unity and the connection between the movement forms of substance, their lively capacity of mutual transformation, allowed the measuring of different forms of substance through a common aspect: energy.

Energy is one of the most important physical concepts discovered by man. The correct comprehension of the notion is a necessary condition to analyze energetic systems and energetic processes.

Types of Energy
The name of energy forms is related to:
1. The way energy is perceived (for example: mechanical energy, electrical energy, energy of light)
2. What carries the energy (for example: thermal energy)
3. The origins of energy (for example: nuclear energy, hydraulic energy, wind energy, geothermal energy, and solar energy).

Some general principles can be reminded:
1. Energy is mathematical abstraction, a measure of movement within moving forms changing phenomena.
2. The energy which is available is not always under the form expected. In order to obtain the form you want, you must proceed to conversion. Usually, not all the energy available can be changed into another form of energy.
3. The total amount of energy does not change in the case of any process of moving forms – this is the energy conservation law. This law permits to deduce how a changing system works, if we know the mathematical expressions of different forms of energy.
4. As energy can not be created or destroyed, the sum of energies which enter a process must be equal with the sum of energies which result from the process.

The use of different forms of energy involves knowing the changes from a form of energy to another. Thus it was discovered the fundamental law concerning the irreversibility in time of real phenomena, which allows us find out how much energy is available. Therefore it was introduced the notion of entropy, whose growing during physical processes determines irreversibility.

Physical energy
As a general measure of different movement forms of substance, energy expresses the capacity of a physical system to perform mechanical work when it suffers a change from a state to another. In the middle of the 19th century it was established by experiments that qualitative different forms of the movement change one into the other, in strictly determined quantitative reports. Whenever, during material interaction of corps, a certain equivalent amount of movement disappears, under another given form, it appears an equivalent movement quantity, under another form.

This fact proved the unity and the indestructibility of the substance movement and it allowed the introduction of the energy notion, therefore the measuring of different forms of movement by a common aspect.

Different movement forms are associated to different types of energy (mechanical, electromagnetic, thermal, chemical, nuclear, etc.) and the equivalence of different types of energy, their mutual transformation in determined reports was expressed by the law of conservation and change of energy, which is a particular case of a more general law, that of substance conservation.

Energy is an intrinsic quality of substance, of any physical system, irrespective if it is made of substance, field or both.

Forms of energetic transfer
Energy does not have different forms, as it is usually perceived, as energy is a fundamental property of substance. Even from the grammatical point of view, the word energy can be uncountable.

Some of the best known forms of energetic transfer are the following distinct physical variables:
1. Kinetic energy (energy possessed due to the movement) and Potential energy (energy possessed due to the position) (in Mechanics)
2. Internal energy and external energy (in Thermodynamics)
3. Energy, in relativity (in the Theory of relativity)
4. Mechanical work (in Mechanics)
5. Force moment (in Mechanics)

Other types of energy
Germination energy
It is a feature of seeds expressed by the per cent of seeds germinated normally in 1/3 – ½ of the time established to determine the germination capability.

Energy specific to sense organs
It is an idealist – subjective theory, formulated by the German naturalist J.P. Muller, on the basis of physiological idealism. According to it, the activity of sense organs is not determined by an objective reality, but by a proper energy, detached metaphysically from the outer world.