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Homework Help: Hydraulic press

  1. Sep 18, 2007 #1
    1. The problem statement, all variables and given/known data

    A 55 kg cheerleader uses an oil-filled hydraulic lift to hold four 110 kg football players at a height of 1.0m. 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


    After I did this, I realized that I need to work the height into the equation, but I'm not sure where it would fit in.
  2. jcsd
  3. Sep 18, 2007 #2


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    The simplest way is to think of the volume displaced - since the hydraulic fluid is in incompressible that must be the same for the cheerleader and the footballers.
    In addition the force exerted by the cheerleader and footballers is known.

    area_cheerleader * height_cheer = area_footballers * height_footballers
    55g / area_chearleader = 110g/area_footballer

    The unknowns are area_footballer and height_cheerleader.
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