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Relativistic energy

  1. Jun 3, 2005 #1
    can anyone explain to me wha relativistic is?
  2. jcsd
  3. Jun 3, 2005 #2


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    It means "obeying the Lorentz transformation" which is necessary if your physics covers different inertial frames (as for example, a fast moving subatomic particle and a lab apparatus assumed at rest). This means that energy depends on relative speed.
  4. Jun 7, 2005 #3
    wow sorry i dont no what was wit me when i wrote that forum, but what i ment to ask was can anyone explain to me what relativistic energy is?
  5. Jun 7, 2005 #4
    Seems to me that when someone is using that term they are referring to the sum of kinetic energy + rest mass energy.

  6. Jun 7, 2005 #5
    That's just energy isn't it?
  7. Jun 7, 2005 #6
    Energy (sometimes referred to as "total energy") is an undefined quantity. Its a number associated with a system and this number is a constant. Energy is made up of various forms of energy each of which are well defined. One form is kinetic energy, one is mass-energy, one is potential energy etc. The quantity

    E = K + E0

    may be what you're thinking of as "relativistic energy." I can't say for sure because I don't know where you got this term. These terms can have different meanings between different authors. I refer to E as "inertial energy." The quantity W defined as

    W = E + U

    where U is a function of the position of the particle. W is referred to as the total energy of the particle in, say, and electric field. I don't recall ever seening the term "relativistic energy" anywhere. However I've read so much I may have forgotten I've seen it.

    Last edited: Jun 7, 2005
  8. Jun 8, 2005 #7
    Relativistic energy due to observable differences in total energy due to differing reference frames. The total energy of an object is given by the root of (pc)^2 + (mc)^2, so relativistic energy is dependant on momentum, which may change frame to frame.
  9. Jun 8, 2005 #8
    That's true so long as the body is not under stress and has zero potential of position.

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