I am trying to determine the weight of an equipment with fluid of some density $\rho$ and volume $v$. I believe the weight is straight forward and should be $\rho v g$, where $g$ is the acceleration due to gravity. In case of pressure vessels (cylinder), their is also internal pressure, but in the free body diagram they cancel out. How about if the pressure vessel was unsymmetrical?

  • $\begingroup$ See also the more recent question: Hydrostatic paradox $\endgroup$ Sep 29, 2017 at 8:06
  • 3
    $\begingroup$ Unrelated, but I'll mention it for fun: in general relativity pressure does contribute to the weight of an object. That's because pressure is due to the internal energy of the atoms/molecules in the object, and that internal energy contributes a mass given by Einstein's famous equation $E=mc^2$. $\endgroup$ Sep 29, 2017 at 8:10
  • $\begingroup$ @JohnRennie Thank you for pointing me to some of the related questions but their scope is limited to static pressure, how about dynamic pressure, such as a pump that increases the pressure in a pressure vessel? $\endgroup$ Sep 30, 2017 at 5:50
  • $\begingroup$ If the pressure vessel is asymmetric, do you expect it to start accelerating in some direction? $\endgroup$
    – Jon Custer
    Oct 4, 2017 at 13:20


Browse other questions tagged or ask your own question.