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Homework Help: WANTED: Formula for frictional resistance

  1. Jun 29, 2003 #1
    I do remember you folks to like to see where I left things. Well, let's change the arrangement. Give me formula and I will do the rest.

    A hydraulics lift (type commonly used for greasing automobile) consist of a 10.111-in-diameter ram that slides in a 10.006-in-diameter cylinder. The annual space being filled with oil having a kinematic viscocity of 0.0038 ft^2/sec and specific gravity of 0.83. If the rate of travel of the ram v is 0.5fps, find the frictional resistance, F when 6ft of the ram is engaged in the cylinder......

    I think this is simply evaluating expression problem once the expression is known to me. Am I underestimating the question?
     
  2. jcsd
  3. Jun 30, 2003 #2
    Is this what you are looking for?

    Rf = 0.97 x Cf x Sw x V^2 where:

    Rf = Resistance in pounds
    Cf = Coefficient of friction
    Sw = Wetted surface
    V = Velocity in ft/sec
    0.97 = Constant for fresh water

    Source: http://www.greenval.com/shape_part1.html
     
  4. Jun 30, 2003 #3
    I am not sure whether I have the formula I was looking for because the fluid in my problem is oil not the water. I will check out the web site you were referring to. Thanks for your time and kindness.
     
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