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Melting Ice with a Carnot Engine

  1. May 9, 2008 #1
    A Carnot heat engine uses a hot reservoir consisting of a large amount of boiling water and a cold reservoir consisting of a large tub of ice and water. In 5 minutes of operation of the engine, the heat rejected by the engine melts a mass of ice equal to 3.40×10^−2 kg.
    Throughout this problem use L_f = 3.34x10^5 J/kg for the heat of fusion for water.

    During this time, how much work W is performed by the engine?

    I dont know where to start...any help please?
  2. jcsd
  3. May 10, 2008 #2


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    Homework Helper

    Hi horsegirl09,

    What is the efficiency of this engine? You are able to find a numerical value here.

    Once you have that, how is the efficiency related to the work done?
  4. May 10, 2008 #3
    I still dont see how i can get the efficiency without any temperatures or heat values
  5. May 10, 2008 #4


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    Homework Helper

    You do have the temperatures: one reservoir is boiling water and the other reservoir is a mixture of ice and water. What efficiency does that give?
  6. May 10, 2008 #5
    Tc=273 k Th= 373 k
    n = 1- (Tc/Th)
    n = 1- (273/373)
    n = 1-.73
    n = .27 or 27%
  7. May 10, 2008 #6
    n= 1-Tc/Th = W/Qh
    how do i get Qh to get W?
  8. May 10, 2008 #7


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    You know that the exhaust melts a certain amount of water, so from that you can find the heat lost.
  9. May 10, 2008 #8
    thanks i got the answer!!
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