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Homework Help: Conduction Question

  1. Apr 23, 2005 #1
    Approximately how long should it take 8.78 kg of ice at 0oC to melt when it is placed in a carefully sealed Styrofoam icebox of dimensions 27.2 cm x 35.7 cm x 51.2 cm whose walls are 1.20 cm thick? Assume that the conductivity of Styrofoam is double that of air and that the outside temperature is 30.9oC.

    I'm trying to start with the equation:

    delta Q/ delta t = kA* [(T1-T2)/l]

    But I have a volume, and I guess I didn't know if V could replace A, but it doesn't seem like it should. Then even if it could, I would have calculated a J/s. And also, do i need to incorporate a phase change in this problem? Any help would be appreciated.
  2. jcsd
  3. Apr 23, 2005 #2

    Andrew Mason

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    Homework Helper

    Work out the total surface area of the icebox. That is A. You are given the thermal conductivity, k and the thickness, l. Just plug in the numbers to give the rate of heat transfer. You should be able to work out the length of time needed to melt the ice from that.

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