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Why fluid transmit for or less force ? Why it is not act like rigid bo

  1. Aug 20, 2014 #1
    According Pascal law we get force high and low to the applying force.....why fluid not behave like ideal solid body force transfer mechanism............ Mean in fluid,how fluid partical manage grater and lower force to the applied force..........how particle s manage it?
  2. jcsd
  3. Aug 20, 2014 #2


    Staff: Mentor

    Why should a fluid behave like a solid? That assumption doesn't make any sense to me. It isn't a solid, so I wouldn't expect it to behave like one.

    Can you explain why you would think that a fluid should behave like a solid?
  4. Aug 20, 2014 #3


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    Staff: Mentor

    You aren't thinking the basic rules of dynamics that apply to rigid bodies don't apply to liquids, do you? F=ma, w=FD, etc? All apply equally to liquids.
  5. Aug 20, 2014 #4
    I don't say that why fluid behave like solid.......But I say that why force is transfer differently in fluid and solid......
    My view is how particles transfer this fluid?
    Like solid particles manage force F if I give F force on it on its line of action.

    But in fluid if I give F force then its output come higher or lower then our input force...so How particle make it......Just think about force transfer in fluid particle....
    I also know abt w=f.d=p.v.......forgot this.........

    Just think what difference in transmission of force in solid and fluid.....Explain how force transmit in fluid by fluid particles that make higher or lower value of output force.....?
  6. Aug 20, 2014 #5
    Have you answer?
  7. Aug 20, 2014 #6
    Sir.. .Read my following post.......I m not making solid=fluid...........but I say fundamentally about particle behavior on force transfer mechanism.
  8. Aug 20, 2014 #7


    Staff: Mentor

    OK, my question stands. Why do you think force transfer should be the same in a fluid and solid?

    To me your expectation that they should transfer force the same seems strange. If you can explain why you think that they should be the same, then I can probably help identify your mistaken assumption or reasoning.
    Last edited: Aug 20, 2014
  9. Aug 20, 2014 #8

    Give answer how force transmit In fluid..?..if you know...

    Your question is good.
    Ideal Fluid= which can be flow...which carry no shear stress at all.
    Solid= rigid or soft body.

    Consider ideal solid and ideal fluid..............okey
    You may be know how sound (pressure wave) transmit in solid and fluid......same mechanism and this mechanism is of compression of particles body....so they manage force equal to apply force and transfer to next particle plane......

    Mechanism is same if you consider ideal solid or liquid..... Even whatever body.........they transmit like same manner.......May YOU KNOW about STRENGTH OF MATERIAL...............
    I hope you understand my questions rather then .....

    Actually force transfer mechanism is same for all body because law have continuity............. Expect any special case......because momentum conservative you know that this law is same for classical and quantum mechanics....Right..

    So my question in short.....

    how fluid give different values of output forces...after input force.......?
    Explain this in fundamental way using of fluids particles.

    I don't say 'why?' But I say 'how?'.....
    Give answer of 'How'...................because your question made by 'why'....its answer is nature make it as it...

    Forgot all....give me answer..

    How applied force will be transmit in ideal fluid and make different output force ?
    (What is behavior of fluid particles in fluid that make pascal law?)
  10. Aug 20, 2014 #9


    Staff: Mentor

    It seems like this may be the misunderstanding that is causing your mistaken assumption. Sound waves propagate differently in solids and fluids. Specifically, fluids can have only longitudinal waves while solids can have both longitudinal and transverse waves. This is because in fluids shear stress is proportional to shear rate while in solids shear stress is negatively proportional to shear strain.
  11. Aug 20, 2014 #10
    Wave transfer mechanism fundamentally same
    ('due to deformation or Change in position of particle,this change due to force)......
    I think you why you don't have fundamental approach.

    Fluid have also transverse wave at starting point....and its effect is eliminate by sher action.....transverse wave lost this way in fluid....

    Have you answer of my question??......
    Plez don't think abt other..
    Give me answer of following...

    why,we get different amount of force at output in fluid....how molecules done this job?
    (explain to me by using force transfer mechanism in fluid)
    (Alone molecules it self is rigid...you can consider it as rigid particle.)okey.

    Be fundamental
  12. Aug 20, 2014 #11


    Staff: Mentor

    The wave transfer mechanism is not the same and ideal fluids do not have transverse waves. This seems to be the key mistaken assumption. You will have to let go of your incorrect assumption before you can progress.

    All the differences between the mechanical behavior of solids and fluids stem from the fundamental fact I mentioned earlier: in fluids shear stress is proportional to shear rate and in solids shear stress is proportional to shear strain. All the other mechanical differences stem from that fundamental difference.
  13. Aug 20, 2014 #12
    OK Sir..what should I do to solve this.? how to understand this pascal law?which give different value of forces with respect to input force..?
    Equation is not my satisfaction....... I need clear picture of it....How this happen,,,,,,
  14. Aug 20, 2014 #13
    It is because of the molecular composition of water.
  15. Aug 20, 2014 #14
  16. Aug 20, 2014 #15
    Yes friend...I think that..but how fluid generate different amount of force..........If we consider fluid make of so many particles ,,so after this,this will be simple problem of mechanics (force transfer)....?I know practically this happen....I also know pascal equation...

    But how can I know what is actually go on in fluid which cause this type of effect!
  17. Aug 21, 2014 #16


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    Homework Helper

    For both a fluid and a solid, compression coexists with a very small increase in density, and an increase in internal pressure in the case of a liquid. For a solid, the term would be strain, a type of deformation which may be restorative (it returns back to it's orginal shape once the stress is removed).
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