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B Could these statments define energy?

  1. May 31, 2016 #1
    A.Energy is a concept that quantifies the amount of work previously done on an object as well as the amount of work than an object can perform (both of which are equal). B. Energy must always be transferred by the means of a physical force. C. All forces cause work from a macro perspective viewpoint. Forces can only be exerted by objects that have had work preformed on them previously.

    If the total energy in the whole universe was and will be constant through all time then does that mean that there is a fixed center of mass of the universe?
    Last edited by a moderator: May 31, 2016
  2. jcsd
  3. May 31, 2016 #2
    Fixed in respect to what?
  4. May 31, 2016 #3
    To change the center of mass of a system of objects( I this case the whole universe) there must be an input or out put of energy, therefore is it true that the center of mass of the universe has been and will be at the same position on a 3 demensional plane for all of time.
  5. May 31, 2016 #4
    No, to have the center of mass moving with constant speed you don't need any input of anything.
    But before even talking about motion and rest you need a reference frame.
  6. May 31, 2016 #5


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    Staff: Mentor

    No, the universe has no known center of mass. It also has no known center or edge.
  7. May 31, 2016 #6
    Ok the center of mass part of the statments is incorrect, but what about the energy statments?
  8. May 31, 2016 #7
    What energy statements?
  9. May 31, 2016 #8
    At the top of the page A B C
  10. May 31, 2016 #9
    As heat is a form of energy transfer that correspond to no macroscopic work, your 2 and 3 seem to be contradictory.

    What are trying to do, anyway? Make e new "theory" of energy?
  11. May 31, 2016 #10
    The amount of work done is the change in kinetic energy of the object the work is being done on. That is not necessarily equal to the amount of work the object can do, because the change in energy is not always equal to the total energy. Correct me if I'm wrong. Work=Force times displacement caused while the force was exerted. The energy is not the maximum amount of work an object can do, because doing work requires changing the energy by adding an external force (an object in rest cannot just suddenly do work), not using the energy.
    Last edited: May 31, 2016
  12. May 31, 2016 #11
    To respond to Nasu, the transfer of heat energy requires the collision of particles, thus work must have been preformed to cause a higher average kinetic energy in the particles until they moved and collided with another to transfer kinetic energy to the other's particles.
  13. May 31, 2016 #12
    But you say "All forces cause work from a macro perspective viewpoint".
    Do you call the work done when two molecules collide a work "from a macro perspective"?
    Then what is not "macro" in your conception?
  14. May 31, 2016 #13
    All matter had to have work applied on it to simply exist( movement of all subatomic particles into position) I am simply saying defining the total energy in an object at a particular instance of time in part A.
  15. May 31, 2016 #14
    Heat is partially work, though, right? Heat is random vibration, but some of the vibration will be in the direction of the force exerted, so by heating something up, work is being exerted (the collisions of the particles exert a force on each particle). Sorry if I'm wrong.
  16. May 31, 2016 #15
    Now you are even more confusing. So what happens if there is no work done on some piece of matter? It does not exist anymore?

    Maybe you start by saying what are you trying to do? You think you have a new definition of energy? Or something else maybe?

    Actually my message was for the OP but you posted in the meantime.
  17. May 31, 2016 #16
    No, it is just at absolute zero, which is impossible. Either that or it is in a perfect vacuum, which is impossible, at least in the perspective of the universe.
  18. May 31, 2016 #17
    No, heat is heat and work is work. See the second law of thermodynamics.
    You can have heat transfer without any macroscopic work. See isochoric transformation of a gas, for example.
  19. May 31, 2016 #18
    You are confused about the concepts of work or maybe you used the term in an unusual way.
    I cannot make sense of this statement.
  20. May 31, 2016 #19
    In order for there to be no heat transfer by convection or conduction, you must have the object in a perfect vacuum or be at absolute zero temperature (meaning no vibrations; this would also remove heat loss by radiation). It was because of these statements:
    Also: http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/heat.html
  21. May 31, 2016 #20
    But I don't see how the absence of heat transfer by convection or any other mechanism is relevant to the main discussion. Assuming that there is a main discussion. :)
  22. May 31, 2016 #21
    Yeah, it got a little off topic with everyone arguing.
  23. May 31, 2016 #22
    Matter as we know it(electrons, protons, neutrons) do not exist unless work was previously exerted on the constituent particles to bring them together? If this is true then we can use the oversimplified expression E=mc^2 to quantify the amount of work that was done simply in the sense of assembling the mater into something we can recognize.

    By macro perspective viewpoint I mean taking all objects in the universe into consideration when ever an action takes place. Not from the viewpoint of a singular object.

    To get back on topic do A,B,C define energy?
    Last edited by a moderator: May 31, 2016
  24. May 31, 2016 #23
    So you don't see the contradiction between B and C, when heat transfer is considered?
  25. May 31, 2016 #24
    So let be explain B anC better
  26. May 31, 2016 #25
    What are you goals, anyway?
    Are you dissatisfied with the standard definitions of various forms of energy?
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