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Homework Help: Minimum horsepower problem

  1. Nov 13, 2009 #1
    1. The problem statement, all variables and given/known data

    In order to keep a leaking ship from sinking, it is necessary to pump 12.0 of water each second from below deck up a height of 1.50 and over the side.

    What is the minimum horsepower motor that can be used to save the ship?

    2. Relevant equations


    1 horse power = 746w

    3. The attempt at a solution
    = mg*d
    = (12*9.8)(1.50m)=176.4

    176.4w(work) / 746w(horsepower) =0.23646..

    p=0.236 hp

    I can't see what did I do wrong. help me!
  2. jcsd
  3. Nov 13, 2009 #2


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    Homework Helper

    pierra, it looks like you found the Work rather than the power - better to start with a P = formula.
    P = W/t = F*d/t would be a terrific start.
    Convert the answer to horsepower.
    You don't say what units the "12.0 of water" is in and I wonder if that is the trouble with the answer (if it is wrong). You'll need the amount of water in kg to put in for the mass.
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