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What is enery excatly?

  1. Jun 18, 2003 #1
    Dear readers,

    As all of us know matter is made up of atoms and we have a very clear idea of it. But when it comes to energy we know a very few about it. Enery is what? the defnition the ability to do work is not a complete defnition. so i want to know more about it. i am a beginer so please go easy on me i would be happy if any one is able to explain this clearly.:smile:

  2. jcsd
  3. Jun 18, 2003 #2
    First of all, welcome to the forums.
    Well, what you seem to be conveinced in (matter) is actually thought to be Energy (according to some of Einstein's theories).
    But, let me explain a little bit more where did the concept of energy come from.
    Through-out time, human noticed that there is something weird that is tranported between objects, so for example a moving billiard ball can move another billiard ball when it hits it.
    With time, human was able to establish relations and laws of how this weird something flows between objects.
    So, fromt he results that this weird something shows on the objects that possess it, we were able to calculate how much of it there is.
    And, we called this Energy :smile:; the ability to do work.
  4. Jun 18, 2003 #3
    dear staii,
    I thankyou for inviting me. ok i understood a bit from you explanation but what do you think about energies like light heat etc.
    please help me.
  5. Jun 18, 2003 #4
    I am glad that you are happy being in the forums.

    Btw, i would be happy if someone answers your questions too, cause i am not really an expert and i might get into errors !

    Ok, well the explaination in my last reply was only an example (the billiard balls).
    Human actually found lot of connection between objects that ended up to be energy transfer, this is why the energy concept is very usefull, because by knowing the energy of an object you can know lot of variables about it (for example, but knowing the lost energy in your muscle while jogging, you can know how much you heated your enviroment, by knowing the speed of the bullet that hit the tree (and therefore its kinetic energy), you can know how hard the sound will be ... etc).
    You asked about heat, heat is actually the kinetic energy of the atoms/molecules making up the object, so, imagine a room full of billiard balls, and all of the balls are moving and colliding, it would be just the way it looks inside an object when you look at the atoms/molecules, and the billiard balls will represent the atoms/molecules, and the kinetic energy of all the billiard balls would be the heat energy of the body . (there is only one diference, the atom/molecules making up and object don't collide by hitting each other, but because of the electrostatic forces between the atoms/molecules (because of the electrons making up the shells of the atom)).
    About light, scientists discovered that light (and all other electromagnetic waves) will decrease the total energy of an object emiting it, and will raise the total energy of and object absorbing it, this is how the connection between light and energy came (actually, light itself is made of energy).
  6. Jun 18, 2003 #5
    Energy is simply the ability to do work.
    What is work?
    Work is the exertion of force over a distance.
    What is force?
    Force is the change in momentum of an entity with respect to time.
    What is momentum?
    Momentum is a relative measure of the inertia of one system with respect to another.
    What is inertia?
    Inertia is the resistance of an entity to change in state of motion.
    What is motion?
    ... ad infinitum

  7. Jun 18, 2003 #6
    Energy cannot be created or destroyed. Energy can only be transformed from one form into other. Matter is energy. Thus,
    Energy is capacity to transform energy. Doesn't say much.

    Yet, nothing, nothing can escape fundamental necessity: interaction. Thus, we can think of energy as of quantifiable measure of mutual interaction. Conditions of interaction dictate 'amount' of interaction, or energy exchange, and mutual change fixes conservation as natural outcome.
    Is there any reason to think about energy as some substance, if in any case conditions dictate energy exchange, not amount of energy dictating conditions? Nope. So, energy isn't real, its our measure of interaction of something.

    layman said
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