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Fluid question

  1. Dec 3, 2003 #1
    Hi everyone….I have a new question. I am writing a lab write-up and I am kind of confused about a concept. In this lab I studied the even flow of water by analyzing the flow of water through a Bernoulli’s pipe. The pipe was set up in a way that it was vertical, open at the top (where a hose rested, which allowed water in) and at the side of the pipe a small hole….where water was projected out. I allowed the water to flow through the pipe in a condition of dynamic equilibrium. In this state, the rate of the flow of water into the top of the pipe equaled the rate of the flow of water out of the side of the pipe. From my measurements, I was able to determine the speed of the water emerging out of the pipe through the hole by using three different equations to verify my results. These equations where: kinematics equation (projectile motion), Bernoulli’s equation, and the equation of continuity (R=Av).

    My question is….there was a correlation between the speed and the height of the water in the pipe. The higher the water in the pipe the faster the speed of the water coming out of the hole. Does anyone know why that is the case.

    Is it because water is entering the pipe at a faster speed, therefore the water coming out of the pipe at a faster speed. Or, is it because there is more water flow entering the pipe, therefore more of a flow coming out of the side hole???
  2. jcsd
  3. Dec 3, 2003 #2
    I believe it's because the more water in the tank, the more potential energy it has. Therefore, for energy to remain constant, the potential energy (which is greater when water is higher) must be converted into kinetic energy with no loss, which will increase the velocity at which it flows from the hole.

    I believe this is the reason but we just covered this subject a week ago in my class so I could be all wrong. Hope it helps.

  4. Dec 3, 2003 #3
    Thanks...that make since to me.
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