Does capillary rise violate hydrostatic paradox?












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If $p$ is a pressure and $p_A = p_{text{atm}} + hdg,,$ $p_B = p_{text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?



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  • $begingroup$
    So P(A) need not be equal to P(B)???
    $endgroup$
    – Lelouche Lamperouge
    Mar 19 at 16:41






  • 2




    $begingroup$
    You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
    $endgroup$
    – Dvij Mankad
    Mar 19 at 17:08


















9












$begingroup$


If $p$ is a pressure and $p_A = p_{text{atm}} + hdg,,$ $p_B = p_{text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?



enter image description here










share|cite|improve this question











$endgroup$












  • $begingroup$
    So P(A) need not be equal to P(B)???
    $endgroup$
    – Lelouche Lamperouge
    Mar 19 at 16:41






  • 2




    $begingroup$
    You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
    $endgroup$
    – Dvij Mankad
    Mar 19 at 17:08
















9












9








9


1



$begingroup$


If $p$ is a pressure and $p_A = p_{text{atm}} + hdg,,$ $p_B = p_{text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?



enter image description here










share|cite|improve this question











$endgroup$




If $p$ is a pressure and $p_A = p_{text{atm}} + hdg,,$ $p_B = p_{text{atm}}$, is hydrostatic paradox violated, shouldn't $p_A=p_B$?



enter image description here







fluid-statics capillary-action






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edited 2 days ago









Qmechanic

106k121961224




106k121961224










asked Mar 19 at 16:26









Lelouche LamperougeLelouche Lamperouge

905




905












  • $begingroup$
    So P(A) need not be equal to P(B)???
    $endgroup$
    – Lelouche Lamperouge
    Mar 19 at 16:41






  • 2




    $begingroup$
    You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
    $endgroup$
    – Dvij Mankad
    Mar 19 at 17:08




















  • $begingroup$
    So P(A) need not be equal to P(B)???
    $endgroup$
    – Lelouche Lamperouge
    Mar 19 at 16:41






  • 2




    $begingroup$
    You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
    $endgroup$
    – Dvij Mankad
    Mar 19 at 17:08


















$begingroup$
So P(A) need not be equal to P(B)???
$endgroup$
– Lelouche Lamperouge
Mar 19 at 16:41




$begingroup$
So P(A) need not be equal to P(B)???
$endgroup$
– Lelouche Lamperouge
Mar 19 at 16:41




2




2




$begingroup$
You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
$endgroup$
– Dvij Mankad
Mar 19 at 17:08






$begingroup$
You must have meant hydrostatic principle rather than hydrostatic paradox. ;) A paradox cannot be "violated"--rather, it appears to violate principles. And true principles resolve the paradox rather than violating it. :P
$endgroup$
– Dvij Mankad
Mar 19 at 17:08












2 Answers
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The pressures at A and B are indeed equal. However, the pressure in the fluid immediately below the curved meniscus is equal to $p_{atm}-hdg$ as a result of surface tension. So the pressure at A is $$p_A=p_{atm}-hdg+hdg=p_{atm}=p_B$$That is, there is a discontinuous change in pressure across the meniscus as a result of the surface tension in combination with the curvature. The pressure on the upper side of the interface is $p_{atm}$ and the pressure on the lower side of the interface is $p_{atm}-hdg$.






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$endgroup$





















    4












    $begingroup$

    $p_A$ is equal to $p_B$ here. The disparity is arising due to the fact that pressure just outside the meniscus is greater than the pressure inside. This is due to the curvature of the meniscus and surface tension.
    This difference is compensated by $hdg$ to make $p_A=p_B$.






    share|cite|improve this answer











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      2 Answers
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      2 Answers
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      12












      $begingroup$

      The pressures at A and B are indeed equal. However, the pressure in the fluid immediately below the curved meniscus is equal to $p_{atm}-hdg$ as a result of surface tension. So the pressure at A is $$p_A=p_{atm}-hdg+hdg=p_{atm}=p_B$$That is, there is a discontinuous change in pressure across the meniscus as a result of the surface tension in combination with the curvature. The pressure on the upper side of the interface is $p_{atm}$ and the pressure on the lower side of the interface is $p_{atm}-hdg$.






      share|cite|improve this answer









      $endgroup$


















        12












        $begingroup$

        The pressures at A and B are indeed equal. However, the pressure in the fluid immediately below the curved meniscus is equal to $p_{atm}-hdg$ as a result of surface tension. So the pressure at A is $$p_A=p_{atm}-hdg+hdg=p_{atm}=p_B$$That is, there is a discontinuous change in pressure across the meniscus as a result of the surface tension in combination with the curvature. The pressure on the upper side of the interface is $p_{atm}$ and the pressure on the lower side of the interface is $p_{atm}-hdg$.






        share|cite|improve this answer









        $endgroup$
















          12












          12








          12





          $begingroup$

          The pressures at A and B are indeed equal. However, the pressure in the fluid immediately below the curved meniscus is equal to $p_{atm}-hdg$ as a result of surface tension. So the pressure at A is $$p_A=p_{atm}-hdg+hdg=p_{atm}=p_B$$That is, there is a discontinuous change in pressure across the meniscus as a result of the surface tension in combination with the curvature. The pressure on the upper side of the interface is $p_{atm}$ and the pressure on the lower side of the interface is $p_{atm}-hdg$.






          share|cite|improve this answer









          $endgroup$



          The pressures at A and B are indeed equal. However, the pressure in the fluid immediately below the curved meniscus is equal to $p_{atm}-hdg$ as a result of surface tension. So the pressure at A is $$p_A=p_{atm}-hdg+hdg=p_{atm}=p_B$$That is, there is a discontinuous change in pressure across the meniscus as a result of the surface tension in combination with the curvature. The pressure on the upper side of the interface is $p_{atm}$ and the pressure on the lower side of the interface is $p_{atm}-hdg$.







          share|cite|improve this answer












          share|cite|improve this answer



          share|cite|improve this answer










          answered Mar 19 at 17:09









          Chet MillerChet Miller

          15.9k2826




          15.9k2826























              4












              $begingroup$

              $p_A$ is equal to $p_B$ here. The disparity is arising due to the fact that pressure just outside the meniscus is greater than the pressure inside. This is due to the curvature of the meniscus and surface tension.
              This difference is compensated by $hdg$ to make $p_A=p_B$.






              share|cite|improve this answer











              $endgroup$


















                4












                $begingroup$

                $p_A$ is equal to $p_B$ here. The disparity is arising due to the fact that pressure just outside the meniscus is greater than the pressure inside. This is due to the curvature of the meniscus and surface tension.
                This difference is compensated by $hdg$ to make $p_A=p_B$.






                share|cite|improve this answer











                $endgroup$
















                  4












                  4








                  4





                  $begingroup$

                  $p_A$ is equal to $p_B$ here. The disparity is arising due to the fact that pressure just outside the meniscus is greater than the pressure inside. This is due to the curvature of the meniscus and surface tension.
                  This difference is compensated by $hdg$ to make $p_A=p_B$.






                  share|cite|improve this answer











                  $endgroup$



                  $p_A$ is equal to $p_B$ here. The disparity is arising due to the fact that pressure just outside the meniscus is greater than the pressure inside. This is due to the curvature of the meniscus and surface tension.
                  This difference is compensated by $hdg$ to make $p_A=p_B$.







                  share|cite|improve this answer














                  share|cite|improve this answer



                  share|cite|improve this answer








                  edited Mar 19 at 21:28









                  Sebastiano

                  329119




                  329119










                  answered Mar 19 at 17:04









                  himanshuhimanshu

                  664




                  664






























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