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Is energy tangible?

  1. Feb 5, 2009 #1
    Is energy a tangible thing? Is energy a physical object? IF it isn't, then what is it?
     
  2. jcsd
  3. Feb 5, 2009 #2

    mgb_phys

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    Depends what you mean by tangible, you can buy and sell it which probably makes it a tangible asset to an accountant!
    We normally think of it as a property of a body, so if you throw a ball it has gained kinetic energy, if you put it on a higher shelf you have given it potential energy - but you haven't changed the nature of the ball
     
  4. Feb 5, 2009 #3

    russ_watters

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    Energy is not an object, it is largely a bookkeeping quantity - a property of objects.
     
  5. Feb 5, 2009 #4
    Energy is more then just a property.
    There is not just kinetic and potential energy.
    In fact every particle, every atom is a form energy.
    e.g. if a hydrogen atom comes in contact with an anti matter hydrogen atom, both atoms will turn into photons. If those photons then hit an object they will be absorbed and turn into heat energy. That heat energy can then be converted into kinetic energy. etc.
    So energy can be very tangible if it's in the right form.
     
  6. Feb 6, 2009 #5
    A book on energy I read years ago started with the sentence
    Energy does not make sense.
    It is a sentiment I somewhat agree with in that deep down I dont really understand it, nor in fact anything and I know this is a sentiment shared by many others.Arguably energy may be tangible in that it is perceptible by touch and it may be real but I do not think it is clear and definite.
    The ancient Greeks referred to earth,fire air and water and today,by analogy,we may refer to matter, energy, space and time and
    part of the ongoing business of physics is establishing links between these big four and although great advances have been and may continue to be made this does not necessarily add to our understanding of what they really are.
    (Wow....I have cracked it..time is water)
     
    Last edited: Feb 6, 2009
  7. Feb 6, 2009 #6
    Energy, space, time, pain, love, ... none of these words refer to any particular thing. The meanings of these words are given by their use in the language (Wittgenstein, Philosophical Investigations).
     
  8. Feb 6, 2009 #7
    Here's an experiment to demonstrate the conversion of gravitational potential energy into kinetic energy, and then converting that kinetic energy into mechanical work, and using that mechanical work to break molecular bonds. Hold a cement block high in the air and drop it on your foot.
     
  9. Feb 6, 2009 #8
    I'm no expert, but here's my thinking on energy. The real experts can correct me.

    Energy is an abstract idea that takes many concrete forms: mass, momentum, heat, position in a field, etc.

    Energy has the property of being conserved. So if you add up all forms and let some time pass, then no matter what happens, the sum will not change (in a closed system).

    Energy flows, i.e., it moves from one object to another (e.g., the flow of heat energy from a hot to a cold object, or one pool ball hitting another). When energy flows it often changes form (e.g., from infrared radiation to "heat" (actually, internal energy)).

    Whenever a net force acts on an object (causing an acceleration), energy flows.

    And there is no possibility of a being made out of "pure energy". (I add this because one often hears the idea in sci-fi or religion.)
     
  10. Feb 6, 2009 #9
    But matter is simply energy, so infact, we are made up of pure energy, in the form of matter.
     
  11. Feb 6, 2009 #10
    You're right. I should have said "pure energy" in the sense of non-material energy (with no rest mass).
     
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