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Homework Help: Fluid Mechanics problem

  1. Aug 17, 2010 #1
    1. The problem statement, all variables and given/known data

    What suction (or negative pressure) is required to support a column of liquid 20 m high? Does this exceed the tensile strength of water?

    2. Relevant equations

    Bulk Modulus = (Change in Pressure/ (Change in Volume/Volume))
    Pressure = Force / Area

    3. The attempt at a solution

    Tensile strength of water = 20 MPa

    Pressure = Force / Area

    Assume column has a diameter of 1 unit.
    The surface area of this column is thus:

    Circumference x Height of column + Area of top of column

    = 62.83 + 0.79
    =63.62 units2

    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
    1. The problem statement, all variables and given/known data



    2. Relevant equations



    3. The attempt at a solution
     
  2. jcsd
  3. Aug 17, 2010 #2

    kuruman

    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Do you know why water rises in a straw when you suck on it?
    If you do, then assuming that you have an extremely long straw, can you calculate how high the water would rise if you had perfect vacuum (zero pressure) inside the straw?
     
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