Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Pressure and area relationship in fluids

  1. Oct 16, 2015 #1
    Hoping to clarify something about this...

    Is it fair to say that you should consider the relationship between pressure and area as a function of whether a fluid is moving or standing still?

    In other words, when a fluid is moving and you decrease the area, the pressure goes down because there is more uniform translational motion in a moving fluid, therefore fewer molecules of the fluid collide with each other.

    Meanwhile, when a fluid is standing still and you decrease the area, the pressure goes up because there is more random translation motion in a resting fluid, therefore more molecules of the fluid collide with each other.

    This seems to defy P=F/A and Bernoulli's equation but makes sense intuitively... help!
     
  2. jcsd
  3. Oct 16, 2015 #2

    JBA

    User Avatar

    In a flowing fluid the total pressure = static pressure + dynamic pressure; so, the total pressure does not change nor does the mass flow change from one cross section to the other smaller one. For a static fluid when the mass does not change but the volume is reduced then there is an a change of total pressure.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook




Similar Discussions: Pressure and area relationship in fluids
  1. Pressure and Area (Replies: 1)

  2. Pressure of fluid (Replies: 8)

Loading...