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Homework Help: Food-energy to Mechanical Energy

  1. Dec 18, 2009 #1
    1. The problem statement, all variables and given/known data
    The nominal food-energy value of 1.00g of butter is about 7.20 food calories.

    If all this energy could be converted completely to mechanical energy, how much butter would be required to power a 65.0kg mountaineer on her journey from Lupine Meadows (elevation 2070m) to the summit of Grand Teton (4196m)?


    2. Relevant equations
    Mass*Gravity*Height


    3. The attempt at a solution

    What I tried was (65 * 9.81 * 2126) to find the Joules of energy required for the journey. Then converted 7.2 food calories to 30.1248J and divided to find the grams.

    I came out with approx 4.5x10^4g of butter, however it is not being accepted as correct.
    What am i doing wrong?
     
  2. jcsd
  3. Dec 18, 2009 #2

    Doc Al

    User Avatar

    Staff: Mentor

    Note that food calories are really Kcals = 1000 calories.
     
  4. Dec 18, 2009 #3
    Yep that solved it...

    Thank you for the correction!
     
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