Conduction problem

  1. The temperature in an electric oven is 160 °C. The temperature at the outer surface in the kitchen is 38.6 °C. The oven (surface area = 1.44 m2) is insulated with material that has a thickness of 0.0249 m and a thermal conductivity of 0.0405 J/(s m C°). (a) How much energy is used to operate the oven for 3.88 hours? (b) At a price of $0.10 per kilowatt-hour for electrical energy, what is the cost (in dollars) of operating the oven?

    OK I know to use the Conduction of Heat Through A material on this problem

    Q = (k A Delta T) t/ L

    After plugging in my values Q = [.045 J/ (s.m.C (degrees)] (1.44m ^2) (160 degrees - 38.6 degrees)(13968 sec) (hours converted to seconds) / 0.0249 m

    I get my answer to be 4412945.581 J? This should be my energy value right? The Q in this case is my energy expenditure?

    I plugged this answer in for the webbased solution but it was incorrect.

    Thanks for ur help

  2. jcsd
  3. OlderDan

    OlderDan 3,029
    Science Advisor
    Homework Helper

    Ya gotta use da right numbas
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