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Thread: Weight of heat

  1. #1
    Join Date
    May 2004
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    Weight of heat

    Suppose I weigh a tungsten ingot at room temperature and it weighs one kilogram.
    Then I heat it up to white-hot temperature.
    Will it gain one ppg (part per gazillion...scientific term) from the heat energy?
    SHARKS (crossed out) MONGEESE (sic) WITH FRICKIN' LASER BEAMS ATTACHED TO THEIR HEADS

  2. #2
    Join Date
    Sep 2005
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    Quote Originally Posted by Tom Mazanec View Post
    Suppose I weigh a tungsten ingot at room temperature and it weighs one kilogram.
    Then I heat it up to white-hot temperature.
    Will it gain one ppg (part per gazillion...scientific term) from the heat energy?
    Tom. Yep, it's just Einstein's E=mc2, rearranged, by dividing both sides by c2....the mass is tiny, because the term has a small energy numerator in Joules.
    A joule is units of (kg)(m2 )/ seconds 2.....and ..................................... .................................................. squaring the velocity of light gets you ~ 90 quadrillion = 9.0 1016 m2/ sec 2

    so you plug in your energy increase in joules, and it's a tiny mass increase. You can look up the specific heat of tungsten....then multiply your mass, 1 kg, times the specific heat, times the diifference between room temp and tungsten's melting point (assuming no heat lost), to get your energy added in Joules, then divide by the ninety quadrillion, and the units will cancel to get your kgs.

    pete
    Last edited by trinitree88; 2019-Oct-28 at 05:33 PM. Reason: calculation

  3. #3
    Join Date
    Jul 2010
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    79
    Why use special relativity (E =mc2) instead of general relativity's version which would add the affect of momentum?

    Mark

    OK I think I solved that but I'll leave the question up

    M

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