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Homework Help: Bernoulli Principle of fluid question about velocity

  1. Nov 20, 2011 #1
    1. The problem statement, all variables and given/known data
    A dairy farmer notices that a circular water trough near the barn has become rusty and now has a hole near the base. The hole is 0.11 m below the level of the water that is in the tank.
    If the top of the trough is open to the atmosphere, what is the speed of the water as it leaves the hole? Assume that the trough is large enough that the velocity of the water at the top is zero. The acceleration of gravity is 9.81 m/[itex]s^{2}[/itex]

    2. Relevant equations
    [itex]p_{1}[/itex] + [itex]\frac{1}{2}[/itex]ρ[itex]v_{1}[/itex]^2 + ρg[itex]y_{1}[/itex] = [itex]p_{2}[/itex] + [itex]\frac{1}{2}[/itex]ρ[itex]v_{2}[/itex]^2 + ρg[itex]y_{2}[/itex]

    3. The attempt at a solution
    In the question, it said I can assume that the certain velocity is 0. But I don't know which one. [itex]v_{1}[/itex] or [itex]v_{2}[/itex]? Even if one of the velocities is 0 because it is so insignificant, shouldn't that make the other velocity 0 as well?
  2. jcsd
  3. Nov 20, 2011 #2


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    Staff Emeritus
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    Not necessarily. That is what the Bernoulli relationship explains.
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