Talk:Pascal's law

message: ok so volume of a liquid has to be conserved (given it is incompressible, non viscous blah blah) but why should the force per unit area be conserved and be the same in all directions?
Basically if I just model everything as volume conservation and simply try and say that the liquid "en mass" will try to attain a level of minimal potential energy, I still end up with the same results. However to make the assumption that dF/dA is conserved seems off beat to me —The preceding unsigned comment was added by 220.227.207.194 (talk) 09:29, 5 March 2007 (UTC)
thread_title:  Pascal's law concept beats me 

message: This article has worthwhile information in it, but it was extremely poorly written.  I've given it a once over, but someone with more time and experience should deal with it.  Of particular note, I removed two of the entries under applications:
:*'Pascal's burst barrel demonstration': a long and narrow vertical pipe is connected to the contents of a large, sealed barrel. Adding 2x to the pipe increases the pressure throughout the system. Adding a small amount of water to the pipe is enough to burst the barrel.
:* Atmospheric pressure diminishes with height, a fact first verified on the Puy-de-Dôme and the Saint-Jacques Tower in Paris, on the instigation of Blaise Pascal himself.
The first is poorly written enough that I cannot tell what it's trying to say (and I am unfamiliar with the demonstration).  It also appears to be anecdotal at best, and is hardly an "application".  The second is misleading: air is not an incompressible fluid, and is therefore not strictly subject to Pascal's law. -Athaler (talk) 18:05, 19 February 2009 (UTC)
thread_title:  Major Style Revisions Needed 

message: In engineering, the term fluid encompasses both gases and liquids. Typically, gases are compressible fluids (increasing or decreasing pressure can change the volume occupied by a gas), while liquids are incompressible fluids (applying pressure does not change the volume occupied by the liquid). Though in lay language, a fluid is usually construed as a liquid, when a textbook or other source says Pascal's Law applies to fluids, it is covering both gases and liquids—not one or the other.Writeswift (talk) 21:07, 1 May 2014 (UTC)
thread_title:  Terminology 

message: A more correct interpretation, though, is that the pressure change is caused by the change of potential energy per unit volume of the liquid due to the existence of the gravitational field.
It's not at all obvious to a non-physicist how energy sneaks into this simple equation in such a way as to warrant depiction as "more correct". — MaxEnt 19:15, 2 May 2014 (UTC)
replies: text: I know I'm coming in late here. I just happened to notice this from another change. Pressure is potential energy.  It has the potential to do work if allowed to. A piston in a pressurized cylinder can, if allowed, push a block, or turn a crank and be converted to kinetic energy and/or friction-heat.  Until it does some work, it still only has the potential to. I agree that sometimes the conservation of energy thing gets thrown out as an explanation, which may be true, but it is at too high a level for the particular part of the discussion. The basic concept is that any force is has the potential to do work. Hope this helps.  -- Steve --  (talk) 14:54, 18 September 2018 (UTC)
thread_title:  Energy interpretation 

message: Are we sure, that Pascal's law is correct only in incompressible fluids? I've found phrases in literature, that Pascal's law is consequense of law of conservation of energy and is correct for compressible liquids (gases). Dinamik (talk) 14:15, 21 May 2016 (UTC)
replies: text: The problem I see is that for compressible liquids (such as gases), the density changes with pressure, and so the simple form presented on the page (: \Delta P =\rho g (\Delta h)\,) doesn't work. However, the derivative form should: dP/dh =\rho g . Klbrain (talk) 21:12, 31 August 2016 (UTC)
replies: text:  Well another problem is that Pacal law only works for liquid that is not moving. Otherwise we have additional inertia and viscosity terms. In compressible fluids pressure change causes movement Alex Bakharev (talk) 21:02, 9 July 2019 (UTC)
thread_title:  Pascal's law in compressible fluids 

message: This article is a total mess. Under "Definition," it has two inequivalent statements of the law. The second one, stated as an equation, is valid only for fluids in static equilibrium, and is also stated in a mathematical form that makes it invalid except when the fluid is incompressible and the gravitational field is constant. There is a graph, referenced nowhere in the text, with this caption: "Pressure in water and air. Pascal's law applies only for fluids." The term "fluid" is usually defined in physics and engineering to include both liquids and gases, and in any case the graph doesn't demonstrate anything about Pascal's law. I'm adding the { { Expert-subject } } tag.--76.169.116.244 (talk) 17:48, 29 July 2016 (UTC)
thread_title: article needs attention

message: See the elements given in :fr:Crève-tonneau de Pascal : the experiment never was performed by Pascal... Micheletb (talk) 04:32, 3 July 2020 (UTC)
thread_title:  Pascal's barrel 

message: The explanation section does not provide an explanation, just an example.  For instance, there's no explanation of why, when gravity acts only downward, that there should also be pressure on the sides of the container. A conceptual (not just mathematical) explanation is needed.
DrMattB (talk) 02:36, 8 November 2021 (UTC)
thread_title:  "Explanation" Section