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Homework Help: Pascal's principle/pressure/viscosity

  1. Aug 3, 2008 #1
    1. The problem statement, all variables and given/known data
    A large storage tank (diameter 10m) is filled 10m deep with water (density= 1000 kg/m^3, viscosity= 1.0x10^-3 Pa*s). The outlet at the bottom consists of 2 pipes, as shown. The large pipe has a diameter d2= 0.1m, and the smaller have a diameter d3= 0.05m and length of 20m. A pressure and flow gauge at point A indicates an absolute pressure of 1.95x10^5 Pa, and a velocity of 6 m/s for the water inside the large pipe. You may assume points A,B, and C are all at the same height, and that the height is 0.5m above the bottom of the tank.

    Link below takes you to the diagram....

    a) Determine the atmospheric pressure. (Warning: it will not turn out to be exactly 1 atm.)

    b) If the outlet of the small pipe is atmospheric pressure, how many cubic meters of water leave the tank each second?

    c) How long will it take to empty the tank? (Assume the outward flw is a constant for this calculation!)

    d) Find the water velocity and pressure at point B, inside the smaller pipe.

    e) At point C, the storage tank has a square hole, 5cm x 5cm. A little dutch boy is holding a patch in place over the hole. How much force does he have to exert (horizontally) to keep the patch in place? Explain the reasoning.

    2. Relevant equations
    Pascal's Principle
    101.3 Pa= 1 atm
    P = F/A
    P = Patm + ρgd

    3. The attempt at a solution
    Wow... I am baffled as to how I should even start this. Trying to a) brought me to exactly 1 atm so obviously THAT isn't correct. I am at a complete loss...

    Please, someone help?
  2. jcsd
  3. Aug 3, 2008 #2
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