Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Heat physics question

  1. Jun 26, 2006 #1
    If two objects of different kind is placed together, they have the same temperature. Would the amount of energy in the two objects the same too?
  2. jcsd
  3. Jun 26, 2006 #2


    User Avatar
    Gold Member

    It's possible, but not likely. There are all sorts of energy that each can possess independent of the other. If they're of exactly the same mass, then their thermal energy will be the same.
  4. Jun 26, 2006 #3
    The internal energy of an object can be approximated by:

    [tex] U = m C_v T [/tex]

    That should give you an answer.
  5. Jun 26, 2006 #4


    User Avatar

    Staff: Mentor

    Trick question: temperature is a measure of energy (if we're just talking kinetic).
  6. Jun 26, 2006 #5


    User Avatar
    Gold Member

    But that's an if that wasn't specified. Hence the ambiguity of my answer. If, for instance, one was more massive than the other, it's potential energy would be higher. On the lowest level, e=mc^2 applies to both, so the mass is the determining factor.
  7. Jun 27, 2006 #6
    Actually, potential energy is defined as P.E = mgh

    Where the height, h, is referenced to any arbitrary datum. So if you define the ground as your datum, then anything at ground level will have zero potential energy, no matter the mass.

    Another example, an object below ground level (using ground level as the datum) would have negative potential energy.

    So there are two ways a heavier body can have less potential energy than a lighter body.

    If both bodies are above the datum or below, then your statement always holds true.
  8. Jun 27, 2006 #7


    User Avatar
    Gold Member

    True; I oversimplified as well. The point, though, was just to explain that the question isn't answerable in its current phraseology. More information is required.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook