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Homework Help: Heat of fusion

  1. Jan 15, 2007 #1
    a portion of an electirc circuit connected toa 40-ohm resistor is embedded in .2 kg of a solid substance in a calorimeter. The externam portion of the circuit is connected to a 60 V power supply.

    At 80 C the substance begins to melt. The heat of fusion of the substance is 1.35*10^5 J/kg. How long after the temperature reaches 80 C will it take to melt all of the substance?

    I really don't understand how to find time. I get that there's a way to find heat of fusion, but it's already given to me. help plz

    i have originally posted this in the advanced physics but no one helped. maybe someone here will.
  2. jcsd
  3. Jan 16, 2007 #2
    What is the energy delivered per second to the substance?

    Can you find the power of the power supply? (Hint: P=UI and Ohm's Law)
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