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Pressure force is not clear

  1. Nov 12, 2011 #1

    (1) What does it mean to APPLY PRESSURE?? Don't we actually apply force that is interpreted into pressure by dividing it upon area of action???? This question will clarify really the concept of Pascal's principle.

    (2) HOW CAN IT BE A SCALAR QUANTITY ALTHOUGH FORCE IS A VECTOR ONE???? HOW can we say it acts in all directions??!!!!!

  2. jcsd
  3. Nov 12, 2011 #2

    You can think of it that way, but there are "pressures" that do not come from concentrated forces...they are truly "distributed forces" from the beginning...atmospheric pressure, for example...and all pressures due to gases and liquids, for that matter...the pressure inside a tank, inside a balloon, in the pool...


    The reason why a force is a vector is because is has direction. If I push you, that's one thing...if I pull you, that's another thing.

    And yes, compressed fluids apply equal pressure in all directions...the individual components everywhere inside the fluid cancel out, but when they touch a surface the resultant happens to be the normal to the surface.

    I suggest that you take sometime to play with, say, silly putty and observe why when you push in some spot, your "force" causes the putty to expand in all other directions, etc...
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