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Homework Help: Heat radiation problem

  1. Jun 12, 2007 #1
    1. The problem statement, all variables and given/known data

    A spherical black body having R=0.1m and initial temperature T1=10^3 K is cooled by radiation.The surrounding medium is at a temperature T=0K.What time will it take for the temperature of the sphere to drop to T2=100K?
    Given heat capacity is C and density d
    The answer is :

    (CdR/9σ)(T2^(-3) - T1^(-3))

    2. Relevant equations
    3. The attempt at a solution

    I think just application of Newton's law of cooling will suffice...Isn't it?
     
  2. jcsd
  3. Jun 12, 2007 #2
    No, u can't use Newton's law of cooling because the temp. difference is large.
    U can use stefan's law.
     
  4. Jun 12, 2007 #3
    OK,I missed...
    Then how to proceed???
     
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