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

Explain me concept (Fluid Mechanics)

  1. Apr 7, 2010 #1
    It has been told to me that atmosphere exert a pressure (known as atmospheric pressure) on the surface (I'll take water surface here). And as we go down into water (any fluid, but for instance I'm taking water) the pressure increases. And this increase in the pressure is independent of the shape of the container and only depend upon the depth below the surface of a water open to the atmosphere.

    The pressure at depth 'h' below the surface of water is greater than atmospheric pressure by an amount [tex]\rho[/tex].g.h

    Now the confusion begins from here.

    First Question

    If I bend the tube in this way:


    will the pressure will be same at every points having the same height or same depth? Explain if I'm going wrong.

    Second Question


    In case like shown above where the surface of liquid is not in same level can we still say that the pressure at any point having same elevation from the floor is at same pressure.
    Last edited by a moderator: Apr 25, 2017
  2. jcsd
  3. Apr 7, 2010 #2
    For pressure at any depth you add pgh(where h is measured from top) to pressure at the surface of liquid. The U-tube here has different levels because the pressures at the surfaces are different. However if you draw a cylinder at the bottom of U-tube it is at rest so pressure at the bottom of the tube is same. That will hopefully make you think that pressure of at same height from the base of tube have same pressure.
  4. Apr 7, 2010 #3
    You mean the pressure at the same horizontal line is same, no problem how I bend the tube.
  5. Apr 7, 2010 #4


    User Avatar
    Homework Helper

    Yes at the every point in that horizontal line the pressure is the same.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook