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Burning fuel and a motor's efficiency

  1. Oct 13, 2014 #1
    1. The problem statement, all variables and given/known data
    A motor burns 20 liter per hour. the fuel's combustion heat is 6.6E6[cal/liter] (i don't know if it's kcal or cal, but i assume it's cal). the motor produces 40 [Hp], what's the efficiency.

    2. Relevant equations
    1[Hp]=746[W]. 1[W]=[Joule/sec]
    1[cal]=4.186[Joule]

    3. The attempt at a solution
    40[Hp]x746x3600=107,424,000[Joule/hour]
    20[liter]x6.6E6[cal/liter]=13.2E7[cal/hour]
    13.2E7[cal/hour]/4.186=31,533,684[Joule/hour]
    The fuel supplies less power the the motor's output. not true
     
  2. jcsd
  3. Oct 14, 2014 #2

    CWatters

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  4. Oct 14, 2014 #3
    Thanks
     
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