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Homework Help: Bernoulli's Principle- Vertically Aligned Holes

  1. Jan 5, 2009 #1
    1. The problem statement, all variables and given/known data
    A can has two vertically aligned holes in it. The height of the fluid is h, and the heights of the two holes are h1 and h2.
    a) Show that the two streams of water will hit the ground at the same spot when h = h1 +h2.

    b) If you had such a can, how would you keep h constant as you verify the above relationship?

    2. Relevant equations
    Bernoulli's Equation http://en.wikipedia.org/wiki/Bernoulli's_principle
    Bernoulli's Principle- Essentially, where velocity is high, pressure is low. Where velocity is low, pressure is high
    A1V1 = A2V2 The cross sectional area (A) multiplied by velocity (V)

    3. The attempt at a solution
    The solution has something to do with projectile motion in the x direction, and in the y direction. To be perfectly honest, I was in regular physics at the time they learned that concept. I was fed up with the slow learning, and decided to enroll in AP physics.
  2. jcsd
  3. Jan 5, 2009 #2


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    Science Advisor
    Homework Helper

    You may be overcomplicating it. You should assume the size of the holes is small and the pressure depends only on the height in the can. You need to figure out what the exit velocity is as a function of the height of the hole. You can do this just by considering conservation of energy. When a blob of water leaves the can the level of the water drops by the volume of that blob. So the kinetic energy of the blob is the same as the potential energy difference of the blob between the top of the can and the exit point. Then, yes, you have a kinematics problem.
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