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I Bernoulli eq

  1. Nov 26, 2016 #1
    Why is there less pressure if the velocity of the fluid is increased?
  2. jcsd
  3. Nov 26, 2016 #2
    I obtained the answer! It deals with the continuity equation, where the mass of a moving fluid does not change as it flows. Thus, the volume flow rate has to be equal at all times.
  4. Nov 26, 2016 #3
    Nevermind that still does not answer my question. Why is there less pressure when the velocity of fluid is increased?
  5. Nov 26, 2016 #4
    You can look at the Bernoulli equation! Since, the left side of its equation is constant, the right side must equal to each other. If there is a smaller cross-section, there will be a higher speed and in order to make the equation equivalent to the left side of the equation, the P at the right side of the equation must decrease.
  6. Nov 26, 2016 #5


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    Staff: Mentor

    That's one of two parts: that's conservation of mass (flow). The other is conservation of energy.
  7. Dec 7, 2016 #6
    ive often wondered what causes the molecules to accelerate. some say that the neck down is a kind of "velocity filter" and allows the high speed vibrations of the molecules to prioritize the ones pointed in the right direction, through.
  8. Dec 7, 2016 #7
    Been a while since I took physics, but I believe that because the left side of the Bernoulli equation stays constant the pressure must vary proportionally with the velocity. So as the water speeds up, it must exert a lower pressure on its surroundings.
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