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Pascal law of fluids

  1. Dec 30, 2014 #1
    1. The problem statement, all variables and given/known data

    a water filled symetrical container has four pistons , one on each side of area A to keep water in equilibrium

    Now an additional force F is applied to all four pistons . then increase in pressure at the middle of container will be:
    2. Relevant equations
    pascal law: change is pressure is transmitted to whole fluid

    3. The attempt at a solution
    since F is applied from four sides so pressure should have been 4F/A but the solution says F/A
     

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  3. Dec 31, 2014 #2

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    What's the definition of pressure?
     
  4. Dec 31, 2014 #3
    Perpendicular force per unit area..
     
  5. Dec 31, 2014 #4

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    Now apply that definition to the problem.
     
  6. Dec 31, 2014 #5
    but the force is from all sides so either vector sum should be 0
    or if add as scalar it should be 4F/A...
    but the answer is only F/A
     
  7. Dec 31, 2014 #6

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    The force is being applied to a fluid, not a solid. What happens when you stand on a water balloon?
     
  8. Dec 31, 2014 #7
    can you give a more detailed reply to this question....
     
  9. Dec 31, 2014 #8

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    4F/4A is the same thing as F/A. If we're discussing pressure as a thermodynamic variable, it's what is called an intensive variable, independent of the size of a system. Mathematically, it's a scalar. Force has a direction, yes; force per unit area has no direction. Pressure times area has a direction. The scalar-vector conflict may be what's confusing you. Stick with it, and we'll sort it out for you.
     
  10. Dec 31, 2014 #9
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