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Homework Help: Heat Engine Efficiencies

  1. Oct 6, 2014 #1
    1. The problem statement, all variables and given/known data

    Suppose you build a steam engine that exhausted 1000 J of thermal energy while performing 300 J of work. What is the energy input? What is the efficiency?


    2. Relevant equations


    3. The attempt at a solution

    Would this be correct?


    Thermal E Input = work + exhaust = 300 J + 1000 J = 1,300 J




    Efficiency = work output / thermal energy input = 300 J / 1,300 J = 0.231 J


     
  2. jcsd
  3. Oct 6, 2014 #2
    The efficiency does not have units of Joules. It does not have any units, it's a ratio.
     
  4. Oct 6, 2014 #3
    Thanks!
     
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