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Homework Help: Time from Joules and Watts

  1. Oct 5, 2007 #1
    An ice cube is placed in a microwave oven. Suppose the oven delivers 104 W of power to the ice cube and that it takes 32165 J to melt it. How long does it take for the ice cube to melt?

    Following my lecture notes and my textbook ... the formula should be t=(J/W), but that isn't giving me the correct answer. Therefore I assume I am missing a step, can anyone help?
  2. jcsd
  3. Oct 5, 2007 #2


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    What answer did you get?
  4. Oct 6, 2007 #3
    I am getting an answer of 309.3s using your equation which seems correct to me...

    1 Watt = 1 J/s so 104Watts=104J/s

    Then dividing the energy used to melt the ice by the power output of the microwave.
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