739:. Based on the fact that a photon has a zero rest mass, the equations that are given in the present definition of kinetic energy are not very useful to electromagnetic radiation. I must say I agree with Andries. Also, this article is part of an encyclopedia. Why should it be limited to the basic definitions of kinetic and potential energy forms and I see no reason why we are trying to associate energy forms as to being only potential or kinetic. I like the work done by Bensaccount, but I think it needs to be elaborated. Electrical energy, for example, has both forms of potential and kinetic energies. According to "Principles of science", 1966, the most common forms of energy are mechanical energy, chemical energy, heat energy, sound energy (compressional waves), light energy (electromagnetic radiation), electrical energy and nuclear energy. I think if someone would like to expand on these it would be benificial to everyone. --
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displacement/motion of a system molecular or related structures). Energy exists in many forms: electromagnetic (including light), electrical, magnetic, nuclear, chemical, thermal and mechanical (including kinetic, elastic, gravitational, and sound), where, for example, electro-mechanical energy may be kinetic or potential, while thermal energy represents overall potential and chaotic motion energy of molecules and/or related micro structure. "... Energy is the ‘‘building block’’ and fundamental property of matter and space and, thus, the fundamental property of existence. Energy exchanges or transfers are associated with all processes (or changes) and, thus, are indivisible from time." by M. Kostic: "Work, Power, and Energy" article in the
Academic Press/Elsevier's Encyclopedia of Energy <
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570:, makes me think that my comment that I thought would be uncontroversial among people who know physics well might be controversial on this page. The person who wrote "it is best regarded as an abstract quantity useful in making predictions." is entirely in line with the view of most modern physicists (see Richard Feynman's
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The current definition given at the top of the article is simply wrong and very misleading. No physics textbook, unless it was a very bad physics textbook, would ever define it in such a way, as most students paying any attention would immediately recognize the definition to be circular and therefore
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Thus we arrive at the second question. From my limited perspective, it seems like the concept of energy is chiefly useful because it allows us to predict things across problem domains. For example, applying the idea of energy, we can predict how fast a particular resting body would be made to move if
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I have no idea what group of people would find this statement "common" particularly in the general population. Seems like an attempt to create an association which does not yet exist in the general population. This statement may indeed becomme true in the near (or far) future but I do not see it as
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per unit time; at least this is true if one defines operations in the right way. I work out the appropriate definitions in some of my research articles. However, this new computational interpretation of energy is not widely accepted (at least, not yet). Nevertheless I have found it helpful for my
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I suggest that in all such discussions, some basic numericals ought to be given .For example, in the discussion of energy , it will be useful to give the energy content in a non-excited hydrogen atom withrespect to the space occupied by a hydrogen atom ( ie, the average distance between the nucleius
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from overall subject outline, don't know where "energy conservation" would be, Lovins' concept of a 'Negawatt' (watt not used due to performing function with higher efficiency device, such as a
Compact Fluorescent Lamp (CFL)), nor where "energy efficiency" would be from an engineering/policy/public
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It seems to me that the entries on energy conversion, energy quality, energy form, and exergy all have a common theme and may benefit from greater clarification and a possible merge. Exergy aims at a quantification of an energy quality, and energy quality is merely a recognition of the different
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for a very approachable discussion. You could also think of kinetic energy as being a kind of potential energy possessed by moving bodies. Ultimately, they are all just forms of energy, and the distinctions between different 'sorts' of energy are just ways of thinking about energy in different
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Yes, the article lost some good information that is why I reverted it to the latest version of WWoods, I had no time yet to check which edits of
Bensaccount were good and which were bad, but the end result was worse. I think I saw some good edit by Bensaccount but I need more time study them.
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As far as I've been able to gather, the first question is a pretty philosophical one, along the lines of "What is a force?", and has no commonly accepted answer. Nonetheless, attributing energy to various situations enhances and simplifies our theories, so the concept is accepted on pragmatic
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More precisely, work is the mechanical process whereby energy is transfered from one form to another. For example when force from a potential field is applied over a given distance, such that work, W, is applied to the body, the kinetic energy of the body increases by the amount W, while the
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DEFINITION of ENERGY: "Energy is a fundamental property of a physical system and refers to its potential to maintain a system identity or structure and to influence changes (via forced interaction) with other system by imparting work (forced directional displacement) or heat (forced chaotic
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nonsense. This is the current definition given: Energy is defined as the amount of work required to change the state of a physical system.' You'll see that this is nonsense if you look at the definition of work: Work is the energy transfered by force to a moving object.
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I've modified it in the current revision to try to make the text flow better. As an aside, I think it is unhelpful to have an article that takes upon itself to explain what work is about explain only "one definition of work", instead of having a more general discussion.
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Chemical energy is a form of potential energy and therefore should not be in a catagory next to potential energy otherwise it seems like there is kinetic energy, chemical energy, and potential energy and they are all completely different. Same goes for electrical
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The phrase "This page discusses the scientific quantity called energy" is bad wiki format and also conveys that the other page is not. The other page is also about the scientific quantity called energy but more spcifically it is about the source of energy for
167:, which says that the work done on a system is equal to the change in the energy of that system. So while work has units of energy, and is related to energy, it is in a sense only a mechanism for changing the energy of a system. I personally think that both
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I must admit, I'm not the most qualified to edit articles about physics. Nonetheless, the current state of the article is such that it really isn't very useful for the average Joe. I'm hoping that making a few changes might nudge it in the right direction.
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There is no uniform way to visualize energy; it is best regarded as an abstract quantity useful in making predictions. In fact, many recognized forms of energy stored in such an object or system, are not easily detectible by the average
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Consider electromagnetic radiation as a photon -- electromagnetic radiation has kinetic energy due to the velocity of the photon. Consider it as a wave -- The energy is the kinetic energy of the wave. I don't see the problem.
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is either incorrect or unhelpful. (A little of each?) There is obviously a connection between work and energy, but I don't think it's quite that simple. I've tried to give an alternative explanation in the current revision.
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or other sort of product that can carry that energy off. The products of the annihilation will carry off exactly as much energy as the matter and antimatter carried in. That will include the mass energies mc^2. —
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Isn't it inaccurate to give a battery as an example of something having 'electrical energy'? The energy in it is, after all, conserved in chemical form and will only do work after certain chemical reactions occur.
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There is no "uniform" way to visualize anything. Who says that its best to regard it as abstract? As a quantity? Just because the aveage person can not see it doesn't mean it can not be defined. (This is biased.)
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is a form of kinetic energy but I don't believe it. The energy of a foton is E=hf=hc/w = planck constant*speed of light/wavelength The velocity is always the same=300,000km/s. So this can't be kinetic energy??
334:. For example, light is a form of energy which is not matter; it is an electromagnetic wave. Heat is another form of energy (this one is absorbed or released by matter, I convene). When one reads about
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perspective, down to earth. Note that HP and
Phillips Electronics are working on a Light Emitting Diode replacment for incandescent or fluorescent lamps! LEDs are close to immortal and 100% efficient.
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I have a proposed new general definition for energy that can be derived from basic quantum theory. In any quantum system (thus, as far as we know, in the real world), energy can be shown to be the
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It doesn't sound like much of a definition, but it the best that can be done with energy, and with sufficient explanation it is the only definition that makes any sense in the long run. --
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Energy is a very important concept, not easily understood. I see this article evolving while losing some important knowledge contained in earlier versions. Energy is definitely not only a
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a particular amount of heat were completely transformed into motion in that body. Similarly, it allows us to predict how much heat might result from breaking particular chemical bonds.
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If Energy is defined as the ability to do work, I don't think work can be considered as a form of energy. Work is the result of the application of energy, but is not a form of energy.
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Second, and much more important: I feel this article is not yet terribly useful for the non-physicists in the audience. Does anyone have any ideas about how to answer questions like
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I've revised the introduction again, mainly because I was uneasy about the connection between work and energy. After reading the
Feynman reference, I feel that the previous summary
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potential energy decreases by the same amount (W). In this sense, work is not itself energy, but refers to the amount of energy that is transferred from one form to another.--
246:, though, would it? If there were no equations involving energy, would there still be some way to say how much heat is equivalent to how much motion of a particular body?
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Bensaccount, your classification of electromagnetic radiation under kinetic energy is unusual. Could you please provide references for your opinion? Thanks in advance.
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are needed, both because of this distinction and because in higher levels of physics, energy is considered the more fundamental idea while work is abandoned. --
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The amount of energy is determined by taking the sum of a number of special-purpose equations, each designed to quantify energy stored in a particular way.
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In physics, work is a name to describe how much energy has gone in to a task. It is equal to force * distance and is measured in joules, so it definitely
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I disagree, according to the sources I have seen heat is the transfer of thermal energy between two sources. What you are speaking of is thermal energy.
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Without the unifying measure of energy, these comparisons and conversions would be much harder. I don't suppose it would be accurate to say it would be
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Almost any reliable source will tell you that energy can only be in two forms: kinetic or potential. I think this website has what you are looking for.
305:. In the one-dimensional case, that is to say W = ∫ f(x) dx, where f(x) gives the amount of force being applied as a function of the distance moved.
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Bensaccount, please do not remove electric energy and chemical energy again unless you have good reason for that (but I can not think of any).
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452:" is unnecessary, since this is the generally accepted meaning of energy. Also since thermodynamics is the study of energy it is kind of a
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A more in-depth historical analysis than is available through the "What does energy really mean?" link might be interesting as well.
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are a very general classification of energy forms. As stated in the present version of the article, these are mostly useful in
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362:=mC equation) but it is not. Matter is. Mass is a physical property of matter, a quantification number, providing the
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Any comments on the accuracy of this explanation? Any references to articles that might explain this more coherently?
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an abstract quantity important in the analysis of all physical systems, which is conserved in all closed systems.
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Why does the energy concept enter into our theories? (Is it "real"? Is it useful? Why should anyone care?)
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Is that momemtum? And, just to clarify, that integral covers the relativistic and non-relativistic cases?
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It seems to me that work and heat are not energy but rather transfer of energy. An analogy could be how
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thanks, providing reasons for deletions is enough for me. Useful additions don't have to be explained.
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This time I will provide a reason for every edit. I am not done; this article is still really bad.
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yet a part of everyday conversation or speech. Ten or more examples may convince me however.
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Well, if matter and antimatter annihilate, then their energy must go somewhere because it's
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itself is also a form of energy. There is a common misconception about the fact that
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If you wish to start a new discussion or revive an old one, please do so on the
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The way we teach energy and work in our freshmen classes here is using the
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I'm not sure that merging "energy" and "work" was ultimately productive.
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I've merged 'Work' into the 'Energy' article, and set a redirect. --
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The end results were not worse. I will give it another try though.
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What about
Angular Work done, ie Torque * angle swept out? -- Dweir
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could be considered a form of energy, (because of the famous E
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is not merchandise but rather the exchange of mechandise.
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Heat is the random kinetic energy of moving molecules.
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In general, the presence of energy is detected by an
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539:-- Or when there is not a change (it is a
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