help me win a bet regarding subs/water pressure physics

[Godalmighty83]

itl take a while but yep all chambers will fllod and eventually match outside pressure.

doesnt matter if the seal can stand 999.99999lbs, your just slowing the inevitable.

[Penelope_Grey]

OOhhh a physics problem.

Well in reality as the guys have stated all three levels are going to be buggered in effect.

Water is just simply weight, the weight of the water is what creates pressure, a submarine or underwater structure creates a gap which water wants to fill, that is what causes pressure.

You won't get a constant slow leak... no, at first you will, yes, but as the seal on chamber 1 degrades under the pressure of the water forcing its way in, so the severity of the leak will increase. Pressure inside chamber 1 will actually increase further because the air will have nowhere to go as it fills up... except... the source of the leak, air will look to escape through there thus causing more strain, as the water level rises 2 things are happening.

1) the weight of the water will be slowly but surely forcing the seal to allow more and more through.

2) the air in chamber 1 will be compressing increasing strain on your seal weakening it further.

Eventually the seal will burst as it cannot handle the strain and a rapid flood will take place. the fact its 1lb is irrelevant... the end result is the same the only thing is the time it takes to happen.

Once chamber 1 floods the exact same things will happen to chamber 2 but quicker because it is lower down and thus water is heavier and thus more pressure on a seal. The seal on chamber 2 will give out the second quickest and then chamber 3 will give out the fastest.

The entire structure is as good as junk the second you lower it into the sea.

[TarJak]

Originally Posted by Penelope_Grey

OOhhh a physics problem.

Well in reality as the guys have stated all three levels are going to be buggered in effect.

Water is just simply weight, the weight of the water is what creates pressure, a submarine or underwater structure creates a gap which water wants to fill, that is what causes pressure.

You won't get a constant slow leak... no, at first you will, yes, but as the seal on chamber 1 degrades under the pressure of the water forcing its way in, so the severity of the leak will increase. Pressure inside chamber 1 will actually increase further because the air will have nowhere to go as it fills up... except... the source of the leak, air will look to escape through there thus causing more strain, as the water level rises 2 things are happening.

1) the weight of the water will be slowly but surely forcing the seal to allow more and more through.

2) the air in chamber 1 will be compressing increasing strain on your seal weakening it further.

Eventually the seal will burst as it cannot handle the strain and a rapid flood will take place. the fact its 1lb is irrelevant... the end result is the same the only thing is the time it takes to happen.

Once chamber 1 floods the exact same things will happen to chamber 2 but quicker because it is lower down and thus water is heavier and thus more pressure on a seal. The seal on chamber 2 will give out the second quickest and then chamber 3 will give out the fastest.

The entire structure is as good as junk the second you lower it into the sea.

Nice one Pen I had a chat to a guy that manufactures hyperbaric chambers and therefore knows just about all there is to know about pressure seals and he said almost exactly the same thing.

His only caveat was what pressure the "gas" was in the chambers. Even a small amount of air pressure (say at sea level pressure), will increase the amount of pressure needed by the water to make the next seal fail. So (hope I get this right), if the air pressure inside chambers 2 and 3 is ~14psi, then the pressure needs to be 999psi+14psi to make the seal fail.

He said though given that this wasn't specified in the problem description that it may not apply to the problem at hand. He also said that different gas mixtures can also have different effects but that the "gas" pressure is the key. If it was a vacuum then failure would occur.

[Letum]

If the following are variable:
a) Water pressure in all areas
b) Water levels in all areas
c) Air pressure in all areas
d) Seal integrity

And everything else is constant then regarding weather each chamber will fully flood:

Chamber 1 will flood fully if:
a) there is enough water out side the chambers to flood chamber 1 with out the water level out side the chambers falling below the top of chamber 1.

Chamber 2 will flood fully if:
a) Chamber 1 has fully flooded

and

b) The water pressure out side chamber 2 has not decreased below 99.0000[...]001 lbs per unspecified unit of area as a result of a decrease in the water level out side the chambers caused by the filling of chamber 1.

and

c) The air pressure in chamber 2 is less than the water pressure on the seal.

and

d) there is enough water out side the chambers to fully flood chamber 2 with out the water level out side the chambers falling below the top of chamber 2.


Chamber 3 will flood fully if:
a) Chamber 1 and chamber 2 have fully flooded

and

b) The water pressure out side chamber 3 has not decreased below 99.0000[...]001 lbs per unspecified unit of area as a result of a decrease in the water level out side the chambers caused by the filling of chamber 1 and chamber 2.

and

c) The air pressure in chamber 3 is less than the water pressure on the seal.

and

d) there is enough water out side the chambers to fully flood chamber 3 with out the water level out side the chambers falling below the top of chamber 3.

Is that comprehensive yet?

[kurtz]

All chambers will eventually flood what I think has been missed is that the pressure will build up even before a chamber has flooded as the incoming sea will compress the air so the seals would fail (possibly) before they are reached by water. (assuming we modify the experiment to have the apparatus lying on its side as per d@rk51d3suggestion)

PS thanks for the thinking material Sunday was starting to drag

[Bill Nichols]

Whoever chose the second option is gonna lose fifty bucks.

[Letum]

So?
Who won the bet?

[Penelope_Grey]

Originally Posted by TarJak

Nice one Pen I had a chat to a guy that manufactures hyperbaric chambers and therefore knows just about all there is to know about pressure seals and he said almost exactly the same thing.

His only caveat was what pressure the "gas" was in the chambers. Even a small amount of air pressure (say at sea level pressure), will increase the amount of pressure needed by the water to make the next seal fail. So (hope I get this right), if the air pressure inside chambers 2 and 3 is ~14psi, then the pressure needs to be 999psi+14psi to make the seal fail.

He said though given that this wasn't specified in the problem description that it may not apply to the problem at hand. He also said that different gas mixtures can also have different effects but that the "gas" pressure is the key. If it was a vacuum then failure would occur.

Physics and Chemistry are about two of the only things I am good at.

I did wonder about internal air pressure but since nothig was mentioned about the pressure inside the cabins I just left it out as a non-factor. Talking in simple terms though, the thing is junk the second you put it in the water. LOL

Waste of good metal.:rotfl:

[minsc_tdp]

I lost the bet and paid my dues. I consider myself a true scientist (albeit an untrained one) so I'm always willing to start with a theory and seek out information that can prove it either way, and accept the conclusion and change my theories to fit the evidence and the proof like a real man. While it seems like the air pressure is the only wildcard factor here, and the size of the structure may have an effect, for the most part, my myth is busted.

I realize that Pascal's Law is the key here really - "Pascal's law or Pascal's principle states that for all points at the same absolute height in a connected body of an incompressible fluid at rest, the fluid pressure is the same, even if additional pressure is applied on the fluid at some place."

[TarJak]

Originally Posted by Penelope_Grey

Waste of good metal.:rotfl:

Unless you want to anchor a bouy with it. Tho it would be cheaper and quicker to fill the lot with concrete first.:rotfl: