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Homework Help: Heat Transfer Question

  1. Feb 26, 2012 #1
    1. The problem statement, all variables and given/known data

    Consider a brick wall, 4.0 m high, 6.0 m wide and 300
    mm thick, where the thermal conductivity of the brick
    is 0.8 W.m-1.K-1. During a particular one-hour period,
    the temperatures of the inner and outer surfaces were
    measured to be T1 14oC and T2 6oC respectively. The average
    rate of heat transfer

    Q*=Rate of heat tranfer (i think)

    2. Relevant equations

    The equation that I am trying to use is Q* = (T1-T2)*(k)*(A)/^X not sure if correct.

    3. The attempt at a solution

    ^X is just the thickness of material
    A is 4*6=24m^2
    k = 0.8W/mK

    so i filled in and the divided by 3600s to get an answer in joules, i know i have can wrong can someone help me out with what formulae to use for this question?
  2. jcsd
  3. Feb 26, 2012 #2
    You are using the correct formula. A watt is 1 joule/second so you should not divide by 3600. To get joules/hr, multiply by 3600.
    Last edited: Feb 26, 2012
  4. Feb 26, 2012 #3
    Careful with the use of ^. It means exponentiation to most people.
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