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Homework Help: Verifying Hydraulics Question

  1. May 9, 2008 #1
    1. The problem statement, all variables and given/known data
    A 55kg cheerleader uses an oil-filled hydraulic lift to hold four 110 kg football players at a height of 1 m. If her piston is 16 cm in diameter, what is the diameter of the football players' piston?

    2. Relevant equations

    3. The attempt at a solution

    (55kg)(9.80)/(.02 m^2) = (440kg)(9.80)/A2
    A2 = .16 m^2
    .16 m^2 = pi * r^2
    r=.2257 m
    D= .45 m = 45 cm

    Is this correct? I am a little bit confused as to the difference between these formulas:

    p0 + F1/A1 = p0 + F2/A2 + ro*gh This is the one I used because she is just holding them in position and no work is being done.

    for the formula DeltaF = ro*g (A1+A2)d2 You should use this one when the problem involves lifting something (doing work)
  2. jcsd
  3. May 10, 2008 #2
    any thoughts?
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