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Homework Help: Heat transfer through two metal bars

  1. Aug 27, 2008 #1
    The problem statement, all variables and given/known data

    A steel bar 10cm long is welded end to end to a copper bar 20cm long. Both bars are insulated perfectly on their sides. Each bar has a square cross section, 2cm on a side. The free end of the steel bar is maintained at 100 celsius and the free end of the copper bar is maintained at 0 celsius. Find the temperature at the junction of the two bars.

    The attempt at a solution

    The problem is a worked example so I can see the method for solving it. But I don't understand why they take the heat currents through the two bars to be equal? Would someone be able to explain it to me? :)

  2. jcsd
  3. Aug 27, 2008 #2


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    Science Advisor
    Homework Helper

    Hi kidsmoker! :smile:

    Read every word in exam questions :wink:

    the word "maintained" tells you that the system has reached equilibrium …

    so heat in must equal heat out at all points. :smile:
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