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Homework Help: Fluid flow through a pipe - Conservation of mass and/or momentum?

  1. Feb 11, 2013 #1
    1. The problem statement, all variables and given/known data

    3. The attempt at a solution

    So first I found the density of the air coming in and going out. Next I used conservation of momentum with two forces caused by the pressures at the entrance and the exit of the nozzle.

    I end up getting 1004 which is not the same as 1060. If I just use conservation of mass so ρVAout=ρVAin I get exactly 1060. So why is it that conservation of momentum does not work in this scenario?
  2. jcsd
  3. Feb 11, 2013 #2


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    The nozzle is accelerating the flow of the fluid through the restriction. The mass flow into the nozzle is the same as the mass flow out, but the velocity has increased while the density decreases.
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