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Heat Engine Carnot Efficiency question

  1. May 17, 2012 #1
    1. The problem statement, all variables and given/known data
    A heat engine has a carnot efficiency of 0.11. How much internal energy does this engine use in order to do 5.1 x 10^4 joules of work? How much heat does this engine give off/exhaust?


    2. Relevant equations
    (change in)U=Q-W
    W=(change in)E
     
  2. jcsd
  3. May 17, 2012 #2

    rock.freak667

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    Homework Helper

    You need to post your attempt.

    How does W and Q relate to the efficiency?
     
  4. May 17, 2012 #3
    W is the work done and Q is the heat generated. U is the total internal energy. No idea how to do this, hence my non-existent attempt.
     
  5. May 17, 2012 #4
    Still stumped and don't know how to attack problem!
     
  6. May 18, 2012 #5
    Someone PLEASE help?!!?!?!?!? Growing very desperate here.
    EDIT:
    I think I got it.
    Internal energy=412636J, exhaust heat is the same. So sleepy, please confirm.
     
    Last edited: May 18, 2012
  7. May 18, 2012 #6

    rock.freak667

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    Homework Helper

    Look up 'thermal efficiency', that will tell you how Q and W are related to the efficiency n.

    When you know that you can get the value of Q and subsquently U.
     
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