Information AboutEnergy |
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In general the Concept , energy refers to "the potential for causing a change". The word is used in several different contexts. The Scientific use has a precise, well-defined meaning, whilst the many Non-scientific uses often do not. In Physics , ''energy'' is defined as the capacity for doing Work . In Chemistry , ''energy'' is the cause and effect of all interactions between Substances and determines the speed of any Chemical Reaction . In Biology , it is defined as the basis for conducting living processes. In Particle Physics , energy is defined, or characterized, as being one or more of the four Fundamental Forces . is a highly visible form of energy transfer.]] ETYMOLOGY The etymology of the term is from Greek ''ενεργεια'', ''εν-'' means "in" and ''έργον'' means "work"; the ''-ια'' suffix forms an abstract noun. The compound ''εν-εργεια'' in Epic Greek meant "divine action" or "magical operation"; it is later used by Aristotle in a meaning of "activity, operation" or "vigour", and by Diodorus Siculus for "force of an engine". HISTORICAL PERSPECTIVE Energy, in the distant past, was discussed in terms of easily observable effects it has on the Properties of objects or changes in state of various systems. It was generally construed that behind all changes, some sort of energy was involved. As it was realized that energy could be stored in objects, the concept of energy came to embrace the idea of the potential for change as well as change itself. Such effects (both potential and realized) come in many different forms. While in spiritualism they were reflected in changes in a person, in Physical Sciences it is reflected in different forms of energy. For example, Electrical Energy stored in a battery, the Chemical Energy stored in a piece of food, the Thermal Energy of a water heater, or the Kinetic Energy of a moving train. The concept of energy and work are relatively new additions to the physicist’s toolbox. Neither Galileo nor Newton made any contributions to the theoretical model of energy, and it was not until the middle of the 19th century that these concepts were introduced. The development of Steam Engines required engineers to develop concepts and formulas that would allow them to describe the Mechanical and Thermal efficiencies of their systems. Engineers such as Sadi Carnot and James Prescott Joule , mathematicians such as Émile Claperyon and Hermann Von Helmholtz , and amateurs such as Julius Robert Von Mayer all contributed to the notions that the ability to perform certain tasks, called work, was somehow related to the amount of energy in the system. The nature of energy was elusive, however, and it was argued for some years whether energy was a substance (the Caloric ) or merely a physical quantity, such as Momentum . William Thomson ( Lord Kelvin ) amalgamated all of these laws into his laws of Thermodynamics , which aided in the rapid development of energetic descriptions of chemical processes by Rudolf Clausius , Josiah Willard Gibbs , Walther Nernst . In addition, this allowed Ludwig Boltzmann to describe entropy in mathematical terms, and to discuss, along with Jožef Stefan , the laws of Radiant Energy . For further information, see the Timeline Of Thermodynamics . Or you can visit the website at http://www.energy-force.com/ ENERGY IN THE NATURAL SCIENCES In physics, energy is the ability to do Work (work is, simplistically, a force applied through a distance), and has many different forms. Some of the most prevalent of these forms are as follows: -Kinetic energy, the energy of motion (an object which has speed can perform work on another object by colliding with it). -Potential energy, or "stored" kinetic energy. This sort of energy arises when work is done on an object to move it somewhere against an opposing force. For instance, stretching a rubber band increases the elastic potential energy stored within the band. When the band is released, this energy is converted into kinetic energy, and work is performed. Other forms of potential energy include gravitational potential energy (from moving masses apart), electrical potential energy (from moving charges against a field), and chemical potential energy (energy stored within chemical bonds). -Thermal energy, the kinetic energy associated with the various motions of microscopic particles. The average thermal energy within a sample of matter is referred to as the sample's temperature (work is required to accelerate the particles and raise the temperature). -Light energy, the energy that composes photons and is responsible for the various sorts of electromagnetic radiation (work is required to create photons). -Nuclear energy, the energy stored within the nuclei of atoms. No matter what the form, however, physical energy uses the same units as work: a Force applied through a distance. For example, Kinetic Energy is the amount of work to accelerate body, Gravitational Potential Energy is the amount of work to elevate Mass , etc. Because work is Frame Dependent (= can only be defined relative to certain Initial State or Reference State of the system), energy also becomes frame dependent. For example, a speeding bullet has plenty of kinetic energy in the Reference Frame of non-moving observer, but it has zero kinetic energy in Proper (co-moving) reference frame - because it takes zero Work to accelerate a bullet from zero speed to zero speed. Of course, the selection of a Reference State (or Reference Frame ) is completely arbitrary - and usually is dictated to maximally simplify the problem to be dealt with. In Chemistry , energy is the cause and effect of all transformations a Substance can undergo. These transformations can be a Decomposition , Synthesis or a reaction of Molecules or Atoms . A transformation is possible only if the Free Energy considerations are fulfilled. The speed of a chemical reaction is determined by the Activation Energy that reactant molecules have to surmount in order to produce product molecules. In Molecular Biology or Biochemistry , energy is the source of all biological processes and is due to the making and breaking of certain chemical bonds in the molecules found in biological organisms. These bonds are most often bonds in Carbohydrates or parts. Thus glucose and fructose are the main sources of energy for most biological Process . Mass is also considered as a form of energy, because during annihilation or other mass change the equivalent amount of energy ( E = Mc&2 ) is always released. Energy, in the context of natural sciences, is subject to Conservation (law, which is a mathematical restatement of Shift Symmetry of Time ). Thus, energy cannot be made or destroyed, it can only be converted from one form to another, that is, transformed. In practice, during any energy transformation in ( Macroscopic ) system, some energy is converted into Incoherent Microscopic motion of parts of the system (which is usually called Heat or Thermal Motion ), and the Entropy of the system increases. Due to mathematical impossibility to invert this process (see Statistical Mechanics ), the Efficiency of energy conversion in a macroscopic system is always less than 100%. The SI unit of measurement for energy is the Joule, or Newton metre. Conservation and conversion of energy The first law of Thermodynamics states that the total inflow of energy into a system must equal the total outflow of energy from the system, plus the change in the energy contained within the system. In other words, energy is neither created nor destroyed, only converted between forms. This law is used in all branches of physics, but frequently violated by quantum mechanics (see Off Shell ). Noether's Theorem relates the Conservation Of Energy to the Time Invariance of physical laws. The law of conservation of energy, a fundamental principle of physics, follows from the Translational Symmetry of Time , a property of most phenomena below the cosmic scale that makes them independent of their locations on the time coordinate. Put differently, yesterday, today, and tomorrow are physically indistinguishable. The fact that energy is not always conserved in Quantum Mechanics is a property of the the Uncertainty Principle , which relates the mutual uncertainty of time and energy as follows: : As such, quantum mechanical 'violations' of the conservation of energy are not really violations at all, but rather an example of the priority the uncertainty principle takes over more classical laws. Since there is always a degree of mutual uncertainty between time and energy, it follows that the more accurately time is measured, the less accurate measurements of energy can be. When the time scales become small enough that this quantum uncertainty becomes significant, energy may not be conserved. However. within the limits set by the uncertainty principle, conservation of energy holds. As a consequence of Energy Conservation Law , one form of energy can be readily transformed into another - for instance, a battery converts Chemical Energy into Electrical Energy . Similarly, Gravitational Potential Energy is converted into the Kinetic Energy of moving Water (and a Turbine ) in a Dam , which in turn is transformed into Electric Energy by a Generator . In all cases, as long as no energy is allowed to escape from the system, the sum of all the different energies in the system remains constant no matter how many changes take place. An example of the conversion and Conservation Of Energy is a Pendulum . At its highest points the Kinetic Energy is zero and the Potential Gravitational Energy is at its maximum. At its lowest point the Kinetic Energy is at its maximum and is equal to the decrease of Potential Energy . If one unrealistically assumes that there is no Friction , the energy will be conserved and the Pendulum will continue swinging forever. (In practice, available energy is never perfectly conserved when a system changes state; some energy will escape the system and be converted into 'useless' energies such as sound and heat. If this were not so, the creation of Perpetual Motion machines would be possible.) Another example is a Chemical Explosion in which Potential Chemical Energy is converted to Kinetic Energy and Heat in a very short time. Relations between different forms of energy In the context of natural sciences, all forms of energy: Thermal , Chemical , Electrical , Radiant , Nuclear etc. can be in fact reduced to Kinetic Energy or Potential Energy . For example Thermal Energy is essentially Kinetic Energy of Atoms and Molecules ; Chemical Energy can be visualized to be the Potential Energy of Atoms within Molecules ; Electrical Energy can be visualized to be the Potential and Kinetic Energy of Electrons ; similarly Radiant Energy can be visualized to be the Potential and Kinetic Energy of Photons and Nuclear Energy as the Potential Energy of Nucleons in Atomic Nuclei . ENERGY IN TECHNOLOGY Technology is very often concerned with finding ways to harness energy resources and to use them to do useful work. This invariably requires transfer of heat. Work See Also: Mechanical work Because energy is defined in terms of work, a definition of work is crucial to the understanding of energy. ''Work'' is a defined as a Path Integral of Force F over distance s: : The equation above says that the work () is equal to the integral of the Dot Product of the Force () on a body and the Infinitesimal of the body's Translation (). Depending on kind of force F involved, work of this force results in corresponding kind of energy (gravitational, electrostatic, kinetic, etc). For example, the gravitational force F=-m'''g''' acting on a mass m when the mass is elevated from some height h1 (reference height) to the height h2 is therefore: : W = -mg(h1-h2)= mgh2-mgh1 and we call this work by the term "gravitational potential energy" U = mgh. Similar, work by the force F = m'''a''' to accelerate a bullet from zero velocity to the velocity '''v''' is : = mv2/2 and we call this work by the term "kinetic energy" K = mv2/2. Other forms of energy are similarly defined via work. Heat See Also: Heat ''Heat'' is the common name for Thermal Energy of an object that is due to the motion of the constituents - usually Atoms and Molecules . This motion can be Translational (motion of molecules or atoms as a whole); Vibrational (relative motion of atoms within molecules) or Rotational (motion of the atoms of a molecule about a common centre). It is the form of energy which is usually linked with a change in Temperature or in a change in Phase of Matter . In Chemistry , heat is the amount of energy which is absorbed or released when atoms are rearranged between various molecules by a Chemical Reaction . The relationship between heat and energy is similar to that between work and energy. Heat flows from areas of high , Convection and/or Radiation . ENERGY AND ECONOMY per capita per country (2001). Red hues indicate increase, green hues decrease of consumption during the 1990s.]] The way in which humans use energy is one of the defining characteristics of an economy. The progression from animal power to Steam Power , then the Internal Combustion Engine and Electricity , are key elements in the development of modern civilization. Future Energy Development , for example of Renewable Energy , may be key to avoiding the Effects Of Global Warming . ENERGY OUTSIDE THE NATURAL SCIENCES The word Energy is often used in contexts outside the natural sciences. These outside contexts fall into three main categories: the social and psychological sciences, common use, and use within religious or other non-scientific schemas of the world. In general, the term tends to take on a fuzzier and less well-defined meaning when used outside of the natural sciences. Energy in the Social and Psychological Sciences In the context of Economics , the term ''energy'' is used in discussions related to Resources , such as Fuels , Petroleum Products and Electric Power generation that enable us to use machines. In the context of psychology, sociology, politics etc., energy can be in in the form of Emotional Energy , Embodied Energy , and perhaps Psychic Energy . Everyday Use of the Term In the context of common speech, the word energy has many and various meanings. These meanings may mimic the natural science's definition of energy as the ability to perform work, but this is certainly not a rule. For instance, a person who is particularly industrious, spunky, or alert may be described as 'energetic'. The term 'energy' may also connote a sense of emotional stimulation from a person or environment; for instance, a particularly stimulating experience might be described as a 'high-energy situation'. Spiritual Uses of the Term The term 'energy' has many different uses within the conceptual schemes of the various forms of Spiritual . In such contexts, energy is often thought of as the substance which 'powers' life and that spirits are made of (although this is far from a blanket definition that applies to all traditions). The manipulation of this spiritual energy may confer some sort of power, such as the power to heal in traditional and New Age Mysticism . A prime example of this is Acupuncture , which purports to stimulate beneficial effects on the human body by manipulating its natural flow of energy. The word energy is often used as Reiki (in Japanese culture); Qi (traditional Chinese culture) and Prana , Kundalini and Shakti (in traditional Indian spiritual culture). Paranormal researchers will often refer to " Psychokinetic energy" when attempting to explain Paranormal phenomena or the concept of a Spirit or Soul . The psychiatrist and psychoanalyst Wilhelm Reich coined the term Orgone Energy for the non physical energy of consciousness. See also
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