Is the 55 not 18 high and the 90 twenty four inches high ewok? You are also talking about the preasure being applied to a much larger area. In the airstone case the preasure is applied to a very small space and is the same in any size tank I think. I am not 100% sure here and I may be wrong but water preasure is as you say a function of weight which is in itself a function of gravity which is a downward preasure. Perhaps someone with more knowledge in science and such could pipe in and set things straight.
Why are Air Pumps rated 'Up to'?
- Thread starter Rocketman
- Start date
that was basically just a "for instance" darkangel, i know i am treading on iffy ground myself. and the 90 could be filled to the same height as the 55............
just for the sake of arguement..... i don't believe all pressure is equal tho....... but scientifically i am unable to do it atm.
just for the sake of arguement..... i don't believe all pressure is equal tho....... but scientifically i am unable to do it atm.
The bubbles don't care how heavy the water in the tank is. The weight of the water above them is their only constraint. If you have an 18" cube the bubbles have 18" of water on top of them. If you extend the walls so that you have a 48x18x18 tank the pressure on the bubbles remains the same, the weight of the water, and the outward pressure on the sides, changes. The surface area of the bubbles is the same in both scenarios, the surface area of the tank is not.
Darkangel is correct - water pressure in PSI is purely a function of depth. Otherwise just think how terrible the pressure would be 18" down in the sea!
Larger tanks need thicker glass because each piece of glass is longer, and therefore more strength is needed to prevent it from bowing and breaking. Imagine you have a twig 12" long. If you support it at each end, you can easily break it by hitting it in the middle. If you put two supports under it only 2" apart, far more pressure is required to break the twig.
Bracing is also used for strengthing, of course.
It's easy enough to demonstrate, if you don't believe me! Take a large container, such as a large ice cream tub, fill it with water to 4" say, make a hole in the side at the bottom and observe how far the water comes out horizontally as it falls. Then do the same with a washing up liquid bottle with the same depth of water in it. You will find the water emerges with the same force, as long as you make the same size hole.
This site: http://theory.uwinnipeg.ca/physics/fluids/node8.html explains the physics; I draw attention to the sentence: "Note: Only the density of the fluid and the difference in depth affects the pressure. The shape and size of the container are irrelevant. Thus the water pressure 6 inches below the surface of the ocean is the same as it is 6 inches below the the surface of a glass of salt water. "
Larger tanks need thicker glass because each piece of glass is longer, and therefore more strength is needed to prevent it from bowing and breaking. Imagine you have a twig 12" long. If you support it at each end, you can easily break it by hitting it in the middle. If you put two supports under it only 2" apart, far more pressure is required to break the twig.
Bracing is also used for strengthing, of course.
It's easy enough to demonstrate, if you don't believe me! Take a large container, such as a large ice cream tub, fill it with water to 4" say, make a hole in the side at the bottom and observe how far the water comes out horizontally as it falls. Then do the same with a washing up liquid bottle with the same depth of water in it. You will find the water emerges with the same force, as long as you make the same size hole.
This site: http://theory.uwinnipeg.ca/physics/fluids/node8.html explains the physics; I draw attention to the sentence: "Note: Only the density of the fluid and the difference in depth affects the pressure. The shape and size of the container are irrelevant. Thus the water pressure 6 inches below the surface of the ocean is the same as it is 6 inches below the the surface of a glass of salt water. "
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