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Homework Help: Thermo: Newtons law of cooling for radiation

  1. Oct 21, 2011 #1
    1. The problem statement, all variables and given/known data

    A cube of copper of mass 4 kg and initial temperature of 110 oC is set to radiatively cool in an environment of 100 oC.
    (Note: copper has an emissivity of about 0.05. Also, neglect conduction and convection as cooling agents in this problem.)

    The surface area of the cube is .035 m^2



    3. The attempt at a solution

    Before the copper has had a chance to cool, find the net rate of heat transfer of the cube to the environment.

    Using Pnet=Aes(to^4-ts^4), s=stefan boltzman constant, to= temp of object, ts= temp of surroundings, e=emissivity, a= surface area

    (.035)(.05)(5.67*10^-8)(383.15^4-373.15^4)=.215 W

    Is this correct?

    The next part of the question asks for Newton's cooling approximation, which approximation is this I wasn't able to find a formula for it...


    Thanks, and as always help is much appreciated!
     
  2. jcsd
  3. Oct 21, 2011 #2

    ehild

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  4. Oct 21, 2011 #3
    Numerical answer is correct.
     
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