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So if the pressure in a large fish tank 10 meters below water surface is 50 Glitches (didn't have a realistic number so I put an unrealistic unit), and a Pancake batfish stands still there for a while, does it experience pressure equal to 50 Glitches? , The answer should be yes; by looking at the derivation of the formula $P=\rho gh$

This question was an alternate question to whether the Pressure on an object midway in a fluid depends on the area of the object or not, and the answer is No if I'm correct, but I also think that the pressure on the object depends on the area of the container, in other words if the batfish stand still for some more time and walls keep pushing towards it it will feel more pressure, but can't see the formula above saying anything about it, the derivation does though. What do you think?


marked as duplicate by sammy gerbil, John Rennie, GiorgioP, user191954, Jon Custer Mar 10 at 10:43

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  • $\begingroup$ No it is not... $\endgroup$ – user597368 Mar 9 at 6:45

Pressure in water at atmospheric condition isn't dependent on volume but depth (it's evident in the formula $P=\rho gh$ where h is depth), but when you squeeze the tank in on the fish, the water height increases and if the fish still remains at the bottom, the pressure on the fish surely increase at that depth. And it's the force that's proportional to area not pressure: $$ F=PA$$

  • $\begingroup$ If I squeeze the tank into the fish mg (mass of water above the fish x g) increases while the area of the fish is the same, thus pressure is the one increasing and in this case it should be dependent on the area of the container, I hope to modify the formula to account for the changed area of the container/ column weight. $\endgroup$ – user597368 Mar 9 at 6:43
  • $\begingroup$ If you squeeze the tank in on the fish and remove water so the water level remain constant, pressure also remain constant at the depth of the fish. I understand your standpoint, but pressure in an incompressible fluid doesn't work like that. If you fill a piece of straw to its brim and also fill a large container of the same height as the straw to the brim, the pressure at a particular depth in both straw and large container is the same regardless of area. $\endgroup$ – TechDroid Mar 9 at 7:09

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