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Weight of a hot body

  1. Mar 21, 2006 #1
    Consider a spherical hot body having a temperature T, located on one of the pans of a very sensitive balance. It is equilibrated puting a given mass on the other pan of the balance. The temperature T is lower then the ambiental one. The balance is in mechanical equilibrium but out of thermal equilibrium. Does the balance remain in a state of mechanical equilibrium when its temperature equates the ambiental one? The transmission of energy is isotropic.
  2. jcsd
  3. Mar 21, 2006 #2


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    The balance does not remain in a state of mechanical equilibrium - this follows from argments presented in


    It's also been discussed a lot here on the board, you can probably find the past discussions if you look.

    Carlip's formula for "gravitational mass", the intergal of density + 3*pressure, is basically the flat-space version of the more general Komar mass formula which applies to any static metric.
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