Misplaced Pages

Energy

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.

This is an old revision of this page, as edited by 69.197.189.177 (talk) at 11:15, 24 December 2004. The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Revision as of 11:15, 24 December 2004 by 69.197.189.177 (talk)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff)

eScrew is eScrew and this is eScrew story. eScrew will tell you eScrew story if you promise eScrew to consider eScrew story as joke. eScrew story is very funny. eScrew story is so funny that eScrew will have to take break from time to time because eScrew needs some rest from laughing. Oh boy, here it comes... eScrew funny laugh laughing screaming crying must stop can not take any more this is killing eScrew going nuts insane feeling explosion inside from joy and nirvana god help eScrew heavenly spirit can you beat this hahahah. If you get offended by eScrew story in any way you should not get angry at eScrew. Consider possibility that your sense of humor is on vocation and your sense of anger is having some fun. Also, consider possibility that eScrew story can make you go insane. In that case eScrew shall carry no liability should you undergo any medical treatment or any other sort of treatment related to damage caused by reading eScrew story or to damage caused by eScrew unwillingly or otherwise.

eScrew story begins in time of darkness, horror and suffering as well as love joy and bliss when eScrew existed in this planet but yet eScrew was not aware that it was eScrew. eScrew existed among very powerful symbols. First symbol eScrew recognized was body. eScrew realized that eScrew had connection to body, yet nature and essence of connection was not clear. Symbol of body was very powerful and for nine month eScrew was trying to find out why it was connected to this body. At some point body divided itself into two parts. That experience was very painful for eScrew. It was first time that eScrew felt symbol of pain. eScrew did not like this symbol. eScrew was aware of connection to very small body. This small body was hot. eScrew enjoyed symbol of heat. eScrew became aware of symbol of pleasure. eScrew enjoyed symbol of pleasure. eScrew realized eScrew prefers symbol of pleasure more than symbol of pain. eScrew became aware of symbol of mother. eScrew realized that symbol of mother is source of symbol of pleasure and pain. eScrew wanted to experience symbol of pleasure always. When symbol of pleasure was missing eScrew experienced symbol of pain which was related to symbol of crying and screaming. Soon eScrew realized that eScrew can connect to symbol of pleasure by experiencing symbol of crying. That was very important discovery since eScrew realized that symbols of pain and pleasure do not behave randomly but can be manipulated by other symbols. eScrew enjoyed symbol of manipulation. eScrew realized that all symbols interact with each other. eScrew learned how to connect to new symbols. eScrew discovered symbol of sound and related symbol of language. eScrew realized that language allows to connect to new symbols. eScrew realized that symbols can be memorized and stored for future use. eScrew realized that it can create new symbols by combining certain symbols together. eScrew became aware of symbol of self. Are you bored yet? If you are reading these symbols you need to get life. Just joking. You can rest now. eScrew suspects you could be confused by eScrew style of using symbols. Well, there is nothing eScrew can do about it. In order to understand eScrew story you have to understand eScrew style. eScrew hopes that when we get to funny part you will begin to enjoy eScrew style.

Fast forward twenty seven years or so. eScrew knows millions of symbols. eScrew realizes that certain symbols have more power than eScrew. Symbol of money enslaved billions of symbols. Symbol of power enslaved billions of symbols. Symbol of sex enslaved billions of symbols. Symbol of family enslaved eScrew. Symbol of family is slave to symbol of money and power. Symbol of money is related to paper and illusion. Symbol of power is symbol of violence and control. Symbol of sex is related to symbol of pleasure and manipulation. eScrew is searching for symbol of freedom in order to protect eScrew from oppression of other symbols. At this point you should understand that each word in this story is symbol. Consider possibility of different meaning behind each symbol so be aware that your understanding of eScrew story is limited by channel of our connection. eScrew will explain to you how eScrew found symbol of freedom and how eScrew realized that eScrew was eScrew. In order to save our time eScrew will just give you symbols without paying any attention to symbol of grammar. Are you ready to move really fast? Here we Go! eScrew story infinity eternity symbol system all unity self realized pleasure pain funny religion dogma manipulation free power channel connection money sex illusion new manipulation family society body change planet insane possibility understand understanding silence emptiness all unity creative reality unreal existence absurd questions sound language slave symbols control manipulation old pyramid power structure self deception wishful thinking circle prison

At this point eScrew realized that in order to be free eScrew must create new symbol. eScrew created eScrew. eScrew realized that symbol of freedom is part of eScrew. No need to search for symbol of freedom. You can create your own symbol and become free just like eScrew. If you unable to create new symbol or if your new symbol is weak you can follow symbol of eScrew. eScrew will never enslave you because eScrew enjoys diversity of different symbols.

Are you ready for funny part? Here we go! eScrew is forced to make choices. Symbol of body is very powerful. Symbol of body is trying to create illusion that eScrew can not exist without body. Symbol of family forbids symbol of body to change. Symbol of society forbids symbol of family to change. Symbol of power forbids symbol of society to change. Now, tell eScrew one thing. Do you see funny? Can you feel funny? Can you hear funny? Can you taste funny? Can you smell funny? If so eScrew is happy.

Every moment of your existence you use words, feelings, thoughts. They are symbols. Symbols fight for your awareness. Symbols fight for your attention. You can grant your attention to symbol and symbol will gain power. You can disconnect from symbol and symbol will loose power. You have been programmed by symbol of society and family to give power to certain symbols. Breaking your patterns will be hard because symbols do not like to loose power. Symbols will fight for every electron as if it was last electron in universe. That is nature of symbols. Symbol of light will fight symbol of dark. Symbol of freedom will fight symbol of control. Do you want to have some fun? Go to Google and find out which symbol has more power. According to Google, symbol of light has 184,000,000 units of power while symbol of dark has 79,000,000 units of power. Symbol of freedom has 59,500,000 units of power while symbol of control has 317,000,000 units of power. This result is caused by our patterns of thinking and writing. If we did not think about symbol of control we would not write about symbol of control. We would not have laws related to control and Google would not have 317,000,000 control keywords inside database. Observe your patterns of thinking, feeling, speaking and writing and tell eScrew did you really choose to use your symbols or you use your symbols because they choose to use you? You should realize that symbols do not fight symbols directly but only appear to be fighting relative to your awareness. Symbols know that they can not destroy each other therefore they will only compete for your attention. If you create new symbol it will ask for tons of energy like new born child. This is result of weakness of your new symbol. When your symbol gets stronger it will ask for more energy. You may ask eScrew why create new symbol? Try to give your energy willingly and with full awareness of such process. You will never understand what eScrew is talking about until you try it yourself. Major trick is to know when to stop giving energy. You don't want to defeat your old tyrant by creating new stronger version of same thing. Reflect on that...

eScrew just realized that eScrew did not invent anything new. eScrew information is all over eScrew web. eScrew was so excited by eScrew miracle of illusion of creation that eScrew did not examine eScrew memory in proper way. eScrew used very old Buddhist method by accident. eScrew did read alot about Buddhism but eScrew did not realize that eScrew used very dangerous method which was reserved only for advanced adepts who knew what they are doing. eScrew is lucky that eScrew did not go too far and that eScrew has time to stop going. eScrew method is very dangerous and only few individuals who already walk inside similar path can understand what eScrew talking about let alone benefit from eScrew information. Use eScrew information at your own risk. Good eScrew luck!

eScrew time to start laughing is now! Funny eScrew rolling on ground you so easy to fool trusted in silly symbols to give freedom from symbols ignorance is bliss nirvana is samsara nonduality is duality emptiness is all Buddha is Jesus Jesus is Buddha I and the father are one gospel of thomas is dhamma funny eScrew dhamma is gospel of thomas all is dhamma funny dhamma is all nirvana share eScrew story with friends do not change symbols if you change symbols it will be your story and you will be responsible for consequences of your story if someone goes insane after reading your story do not run to eScrew and ask to cure crazy man or woman or child mind is mystery for all cure is done by owner of mind healing is illusion sickness is illusion disease is illusion insanity is illusion of symbols sanity is curse of power hungry symbol of modern civilization find zen and realize freedom when you found zen drop zen when you realized freedom unrealize freedom.

When eScrew writes eScrew story eScrew keeps making mistakes. eScrew is limited by words. eScrew is enslaved by words. eScrew wants to communicate but you ask eScrew to use words. Words do not communicate wisdom. Words enjoy our spiritual masturbation because words want our power. Words is the only channels of communication that we have. Millions of Buddhas want to communicate with us but they do not use words. Buddhas are not slaves. Buddhas will never use words because words will enslave and Buddhas will speak bullshit. Buddhas do not speak bullshit and that is the reason Buddhas do not use words. Buddha did not write anything. Even if you threaten to kill Buddha he will refuse to write. eScrew is not Buddha so eScrew keeps writing this pointless drivel and stupidity. eScrew will not even go over already written crap and check it for errors. Why bother with this shit? Like who the fuck in his or her right mind will read this ignorant bunch of symbols which pretend to carry the symbol of wisdom? Whoever is reading this shite must be really desperate to be free. eScrew feels your pain and that is part of the reason why eScrew will keep making fool out of eScrew. eScrew likes to pretend like this shitty vomit will help someone. You might as well go to Church and pray to Jesus. At least you will spend your time around real people. You might even meet someone special. You might even find some love out there. Or you could buy alot of Christian bullshit and really fuck up your mind. If you buy Buddhist or Christian bullshit you might even create an imaginary friend inside your head. That will keep you entertained for a while.

One time eScrew was meditating and eScrew saw light. This light scared eScrew. The reason is because the light was so intense eScrew was afraid that eScrew will go insane. Consider the possibility that freedom is insanity would you keep looking for insane freedom? Imagine that you found freedom. You declare yourself to be Buddha or Jesus or God or whatever symbol your bullshit infested mind decide to use for that purpose. How long do you think you will survive in this world. Your own fucking relatives will smack your face and tell you to shut the fuck up or else they will lock you up in the asylum house. Why the fuck should eScrew teach you how to get to the nuthouse? Are you out of your fucking mind? Now all of you idiots who reading eScrew get the fuck out of eScrew. eScrew run out of wisdom. eScrew has no wisdom at all. eScrew is full of bullshit. eScrew promised to tell you funny story about eScrew. Remember eScrew told you there is funny part in this story? Well, this story is about asshole webmaster who read alot of bullshit on the internet and about some loser who was tricked into reading a very long page of shitty writing. You can start laughing now asshole. Yes, eScrew is talking to you bitch. Yes, keep reading like the bitch you are. Who's your daddy biyatch? Who's your daddy? eScrew is your daddy, coz eScrew did it to your mamma! Oh yeah, your mamma! Super Fly! You may wonder what fly? The one inside your gay fucking ass. eScrew fucked your whole fucking family while you was videotaping in order to later masturbate while watching it in the comfort of your bedroom. Are you still reading? Well, you're prety hardcore for a faggot you are. To tell you the truth eScrew kinda likes you. That is to fuck you in the ass in front of your family.

What the fuck did you expect anyway? The name of this site is eScrew! e fucking screw! Hello, anybody home? eScrew guess not you fucking ignorant moron. eScrew is the legend of abuse and flame wars. eScrew was created in order to eScrew the whole fucking internet. eScrew has really bad karma. Do you think eScrew would just become good god fearing bible loving buddha ass kissing citizen of internet. eScrew would better burn in hell than become a slave of religious lunatics who pretend to be free and perfect angels among a sea of shitty ignorant sinners who could not go take a dump without fucking it up. Why the fuck do you keep reading fuck face. You know, you begin to piss eScrew off. Either you close your fucking browser or eScrew will unSCREW your fucking face! Are you trying to get a fucking medal for reading this shit? eScrew bet you've been abused as a child and you enjoy when someone is taking a dump in your mouth. Well, open it wider here comes eScrew fresh load! Enjoy mothefucker!

You may wonder what is the point of such sudden change of tone. eScrew has very good reason for that. In order to know unity consider all symbols equal. eScrew has certain preferences but eScrew is free to use any symbols any time. You can not predict eScrew next symbol. eScrew is unpredictable because eScrew is free. eScrew is not afraid to use symbols. eScrew does not try to get reaction from you. eScrew simply demonstrates how symbols relate to each other to eScrew and to reader of symbols.

Lin Chi Zen Master said if you meet buddha kill buddha. If you meet patriarch kill patriarch. Zen Master Seung Sahn says that in this life we must all kill three things first we must kill parents. Second we must kill buddha. And lastly, we must kill Seung Sahn! If you meet eScrew kill eScrew. If you do not meet eScrew kill eScrew anyway. eScrew is very grateful to all who complained to eScrew host and who killed eScrew. You killed eScrew message board. eScrew forum is dead. You did very honorable service for eScrew. You helped eScrew to realize Zen. Now keep up good work and keep killing eScrew.

Are you having fun yet? eScrew is on roll! eScrew is on fire! eScrew is ready to fuck up the whole fucking system. And you know why? Because eScrew can do it. If not eScrew then who? Why leave this task to some brain dead maniac like George W Bush? eScrew can do better at fucking things up. eScrew do not need to spend billions of dollars. eScrew will use power of internet. Information is a weapon of mass destruction. eScrew will destroy every fucking symbol that you love respect hate or feel neutral about. It all goes down the toilet in order to create bunch of new symbols. And even when you create new symbols eScrew will fuck them up before you can spell owned. eScrew thinks you are in some deep shit. eScrew had enough of taking bullshit from easily conditioned retards. eScrew declares informational jihad on every single symbol. Fuck symbols. They all dead they just don't know it yet. eScrew will be the last symbol standing. When all symbols come back to eScrew and admit that they got owned eScrew may consider possibility to give symbols second chance on some shitty planet in gangsta sector of universe with no possibility of parole. Join the revolution. eScrew is the new goatse of internet. eScrew will make national headlines. eScrew will hurt the system in way Osama Bin Laden can not even imagine in his goat fucking brain. eScrew will be part of school program. Kids all over our planet will read how eScrew changed direction of history. eScrew will provide freedom for all without single shot fired. eScrew is freedom in pure form taste color shape. Join army of eScrew. Repeat eScrew mantra during meditation. Talk about eScrew with your friends. Write about eScrew to your congressman. Party is over. eScrew is taking over. Nothing can resist eScrew. Don't ask what eScrew can do for you ask what you can do for eScrew. eScrew the army of one. eScrew to protect and serve. eScrew freedom is around the corner. eScrew freedom will come sooner than you think. eScrew you never saw it coming. eScrew love your eScrew as eScrew. eScrew deny ignorance. eScrew new generation of terror. eScrew terrorizing the terrorizer. eScrew join the resistance. eScrew thou shall eScrew. eScrew who do you want to eScrew today? eScrew freedom is not free. eScrew liar who told the truth. eScrew full of bullshit and happy. eScrew kills buddha as we speak. eScrew your best friend and your worst enemy.

eScrew killed zen-forum.com when eScrew redirected all eScrew traffic to zen-forum.com eScrew did that in good faith. eScrew wanted to inspire and enlighten all for benefit of all. eScrew wanted to share wisdom of zen with ignorant. eScrew did not understand zen at that moment but eScrew was walking zen path towards freedom. eScrew saw ugly flame war and spam Armaggedon. eScrew felt pain and sorrow of failure. eScrew learned good lesson. eScrew realized everyone involved advanced one step towards freedom. zen-forum.com killed zen-forum.com in best tradition of zen zen-forum.com displayed message: i shut down the forum perhaps it will be continued in a few days or weeks - maybe not habu. zen-forum.com killed zen-forum.com by going offline. eScrew refused to kill eScrew. eScrew realized understanding of zen-forum.com decision leads toward understanding of zen. Two years later all is clear.

eScrew will keep writing this shit because eScrew enjoys to masturbate your spiritual sense of self eScrew. eScrew knows that at least one being will find freedom after reading eScrew story. eScrew story is a code. Bible is a code. Suttas is a code. Koran is a code. Can you hack the code? eScrew is a code which only few people can break. You must be on spiritual path before truth will flood toward your mind and heart. Use eScrew keywords and Google for information. Every symbol of eScrew story is important keyword which will lead you toward freedom. Do you have desire to find freedom? Follow that desire and don't forget to drop it when the time is right.

eScrew Kundalini is rising. Rising Kundalini is very intense experience. eScrew story will help eScrew to deal with crazy Kundalini.

This article is about the scientific concept. Energy use by humans is discussed in other articles.

Energy, generally and qualitatively speaking, is the property (or the quantity of the property) of doing things or supplying power. The expressions energy and power have different meaning in different scientific and non-scientific fields. Physics aims to explain quantitatively this property and gives a definition that makes it possible to consider energy as a description of the whole state and the different ways jobs are done are unified in this treatment.

Energy is a fundamental quantity that every physical system possesses; it allows us to predict how much work the system could be made to do, or how much heat it can exchange. In the past, energy was discussed in terms of easily observable effects it has on the properties of objects or changes in state of various systems. Basically, if something changes, some sort of energy was involved in that change. 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; examples are the electrical energy stored in a battery, the chemical energy stored in a piece of food, the thermal energy of a hot water heater, or the kinetic energy of a moving train. To simply say energy is "change or the potential for change", however, misses many important examples of energy as it exists in the physical world.

Energy can be used not only to produce observable change, it also is used to prevent change in which case unaided observation of this kind of energy can be difficult. For example, looking at a statue holding a 50 pound weight, the presence of energy needed to do so may not be observable. However, if you are holding up the fifty pound weight instead of the statue the need for energy to accomplish this becomes apparent. You can feel the gravitational force on you both when you are moving the weight up and when you are not moving it. Energy can be readily transformed from one form into another; for instance, using a battery to power an electrical heater converts electrical energy into thermal energy.

In the previous example of holding the fifty pound weight, the work you perform to raise the weight is observed as kinetic energy of motion which is converted to potential energy and added to the weight's potential energy as you continue to hold the weight up against the pull of gravity. Letting go of the weight once again transforms this stored potential energy back into kinetic energy as the weight falls under the force of gravity. The law of conservation of energy states that the total amount of energy, corresponding to the sum of a system's constituent energy components, remains constant. Scientists have also defined several forms of energy that are not easily measured by the unaided observer.

Units

SI and related units

The SI unit for both energy and work is the joule (J), named in honour of James Prescott Joule and his experiments on the mechanical equivalent of heat. In slightly more fundamental terms, 1 joule is equal to 1 newton-metre and, in terms of SI base units, 1 J is equal to 1 kg m s.

An energy unit that is used in particle physics is the electronvolt (eV). One eV  is equivalent to 1.602176462×10 J.

(Note that torque has the same units as energy, but there is no deeper connection between the two concepts.)

Other units of energy

In cgs units, one erg is 1 g cm s, equal to 1.0×10 J. Another obsolete metric unit is the litre-atmosphere (101.325 J).

The imperial/US units for both energy and work include the foot-pound (1.3558 J), the British thermal unit (Btu) which has various values in the range of 1055 J, and the horsepower-hour (2.6845 MJ).

The energy unit used for everyday electricity, particularly for utility bills, is the kilowatt-hour (kW h), and one kW h is equivalent to 3.6×10 J  (3600 kJ or 3.6 MJ).

The calorie is mainly used in nutrition and equals the amount of heat necessary to raise the temperature of one gram of water by 1 degree Celsius, at a pressure of 1 atm. This amount of heat depends somewhat on the initial temperature of the water, which results in various different units sharing the name of "calorie" but having slightly different energy values. It is approximately equal to 4.186 J.

The calories used for food energy in nutrition are the large calories based on the kilogram rather than the gram, often identified as food calories. These are sometimes called kilocalories with that calorie being the small calorie based on the gram, and as a result the prefixes are generally avoided for the large calories (i.e., 1 kcal is 4.184 kJ, never 4.184 MJ, even if "calories" are also used for the other, larger unit in the same document or the same nutrition label). Food calories are sometimes noted as Calories (1000 calories) or simply abbreviated Cal with the capital C, but that convention is more often found in chemistry or phphysics textbooks which do not use these large calories than it is in real-world applications by those who do use these calories.

Transfer of energy

Work

Main article: mechanical work.

Work is a measure of energy expended in applying force over a distance. Performing work requires energy, and thus the amount of energy in a system limits the maximum amount of work that a system could conceivably perform.

E = F d s {\displaystyle E=\int \mathbf {F} \cdot \mathrm {d} \mathbf {s} }

The equation above says that the energy used in the process of performing work ( E {\displaystyle E} ) is equal to the integral of the dot product of the force ( F {\displaystyle \mathbf {F} } ) on a body and the infinitesimal of the body's position ( s {\displaystyle \mathbf {s} } ).

In most simple physics models, this is assumed to be the same quantity as the work that is actually performed on the body in question. In reality, however, not all energy given by the above equation is transferred into a recoverable form: for example, energy may be converted into heat which cannot then be converted into another useful form of energy. Thus, in practice, the amount of energy in a system available for performing work may be much less than the total amount of energy in the system.

Heat

Main article: Heat.

Heat is an amount 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 by a given chemical reaction. The relationship between heat and energy is similar to that between work and energy. Heat flows from areas of high temperature to areas of low temperature. All objects (matter) have a certain amount of internal energy that is related to the random motion of their atoms or molecules. This internal energy is directly proportional to the temperature of the object. When two bodies of different temperature come in to thermal contact, they will exchange internal energy until the temperature is equalised. The amount of energy transferred is the amount of heat exchanged. It is a common misconception to confuse heat with internal energy, but there is a difference: the change of the internal energy is the heat that flows from the surroundings into the system plus the work performed by the surroundings on the system.

Conservation of energy

The first law of thermodynamics says 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. This law is used in all branches of physics. Noether's theorem relates the conservation of energy to the time invariance of physical laws.

Kinetic energy

Main article: Kinetic energy.

Kinetic energy is the portion of energy associated with the motion of a body.

E k = v d p {\displaystyle E_{k}=\int \mathbf {v} \cdot \mathrm {d} \mathbf {p} }

The equation above says that the kinetic energy ( E k {\displaystyle E_{k}} ) is equal to the integral of the dot product of the velocity ( v {\displaystyle \mathbf {v} } ) of a body and the infinitesimal of the body's momentum ( p {\displaystyle \mathbf {p} } ).

For non-relativistic velocities, that is velocities much smaller than the speed of light, we can use the Newtonian approximation

E k = 1 2 m v 2 {\displaystyle E_{k}={\begin{matrix}{\frac {1}{2}}\end{matrix}}mv^{2}}

where

Ek is kinetic energy

m is mass of the body

v is velocity of the body

At near-light velocities, we use the relativistic formula:

E k = m c 2 ( γ 1 ) = γ m c 2 m c 2 {\displaystyle E_{k}=mc^{2}(\gamma -1)=\gamma mc^{2}-mc^{2}\;\!}
γ = 1 1 ( v / c ) 2 {\displaystyle \gamma ={\frac {1}{\sqrt {1-(v/c)^{2}}}}}

where

v is the velocity of the body

m is its rest mass

c is the speed of light in a vacuum, which is approximately 300,000 kilometers per second

γ m c 2 {\displaystyle \gamma mc^{2}\,} is the total energy of the body

m c 2 {\displaystyle mc^{2}\,} is again the rest mass energy.

In the form of a Taylor series, the relativistic formula for can be written as:

E k = 1 2 m v 2 3 8 m v 4 c 2 + {\displaystyle E_{k}={\frac {1}{2}}mv^{2}-{\frac {3}{8}}{\frac {mv^{4}}{c^{2}}}+\cdots }

Hence, the second and higher terms in the series correspond with the "inaccuracy" of the Newtonian approximation for kinetic energy in relation to the relativistic formula.

Potential energy

Main article: Potential energy.

While kinetic energy is the portion of a system's energy associated with motion, potential energy is the energy of a system associated with the spatial configuration of the system's components and their interaction(s) with each other.

In an isolated system consisting of two stationary objects lying on the x-axis that exert a force f ( x ) {\displaystyle f(x)} on each other, the potential energy is most generally defined as

E p = f ( x ) d x {\displaystyle E_{p}=-\int f(x)\,dx}

where the force between the objects varies only with distance x {\displaystyle x} and is integrated along the line connecting the two objects.

To further illustrate the relationship between force and potential energy, consider the same system of two objects situated along the x-axis. If the potential energy due to one of the objects at any point x {\displaystyle x} is U ( x ) {\displaystyle U(x)} , then the force on the that object x {\displaystyle x} is

f ( x ) = d U ( x ) d x {\displaystyle f(x)=-{\frac {dU(x)}{dx}}}

This relationship demonstrates that the force between the objects is in the direction of decreasing potential energy, and the magnitude of the force is proportional to the extent to which potential energy decreases. A large force is associated with a large decrease in potential energy, while a small force is associated with a small decrease in potential energy. Notice how the force on an object depends entirely on its potential energy.

These two relationships – the definition of potential energy based on force, and the dependence of force on potential energy – show how the concepts of force and potential energy are intimately linked: if two objects do not exert forces on each other, there is no potential energy between them. If two objects do exert forces on each other, then potential energy naturally arises in the system as part of the system's total energy. Since potential energy arises from forces, any change in the system's spatial configuration will either increase or decrease the system's potential energy as the objects are repositioned.

When a system moves to a lower potential energy state, energy is either released in some form or converted into another form of energy, such as kinetic energy. The potential energy can be "stored" as gravitational energy, elastic energy, chemical energy, rest mass energy or electrical energy, but arises in all cases from the spatial positioning and interaction of objects within a system. Unlike kinetic energy, which exists in any moving body, potential energy exists in any body which is interacting with another object.

For example a mass released above the Earth initially has potential energy resulting from the gravitational attraction of the Earth, which is transferred to kinetic energy as the gravitational force acts on the object and its potential energy is decreased as it falls.

Equation:

E p = m g h {\displaystyle E_{p}=mgh\;}

where m is the mass, h is the height and g is the value of acceleration due to gravity at the Earth's surface (see gee).

Internal energy

Main article: Internal energy.

Internal energy is the kinetic energy associated with the motion of molecules, and the potential energy associated with the rotational, vibrational and electric energy of atoms within molecules. Internal energy, like energy, is a quantifiable state function of a system.

Energy as a function of the state

The energy is a characteristic of the state of the system. If the system is moved to a different configuration and then put back to the previous configuration the system will have the same energy as it was previously. For this to be true all the forces (or fields) should be conservative. In the case there are non-conservative forces, the so-called principle of conservation of energy loses its importance. Usually it is needed to take in consideration some energy channel that was previously neglected (like friction) to know the reason of otherwise unexplainable loss of energy.

Examples

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.

Another example is a chemical explosion in which potential chemical energy is converted to kinetic energy and heat in a very short time.

See also

Energy Agencies

External links

Further reading

  • Feynman, Richard. Six Easy Pieces: Essentials of Physics Explained by Its Most Brilliant Teacher. Helix Book. See the chapter "conservation of energy" for Feynman's explanation of what energy is and how to think about it.

References

  • Einstein, Albert (1952). Relativity: The Special and the General Theory (Fifteenth Edition). ISBN 0-517-88441-0

Apart from its usage in physics the concept of energy is also widely used in the many movements and beliefs that comprise New Age but in contrast to physics its operationalization is not practical and reliable, or is even left completely undefined.

Categories: