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Thermodynamics with styrofoam cooler

  1. Feb 13, 2012 #1
    1. The problem statement, all variables and given/known data
    A cubical styrofoam cooler 80cm on a side and 2.0 cm thick contains 2.0kg of ice at 0C. If it takes four hours for the ice to melt what is the outside temperature? K(st)=.02 w/m*K

    2. Relevant equations
    H=-KA (ΔT/ΔX)
    (conductive heat flow)

    3. The attempt at a solution

    Area: 6(a)^2= 6(.8)^2= 3.8m^2
    K(st)=.02 w/m*K

    H=-.02 w/m*K(3.8m^2) (ΔT/.02m)

    So I used the formula for the conductive heat flow, but I still have two unknowns. I know H is ΔQ/Δt, but I am asked for the time. I had two questions in regards to this problem:
    1. for the area do I find the total surface area or just one side?
    2. what temperature change ΔT should I set the ΔQ formula if I am assuming the ice is melting?

    Thanks for the help!
  2. jcsd
  3. Feb 14, 2012 #2


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    First of all, what do the symbols in the formula for the conductive heat flow mean?
    Can you derive that formula?

  4. Feb 16, 2012 #3
    ehild, thank you for your reply and I apologize for this far too late of response. I figured out the answer to this problem after grinding the problem for a while. I am done with my final for the first part of physics! I can not wait for the second part in a week :) Thanks again and talk to you soon.

  5. Feb 17, 2012 #4


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