Amounts of pressure within 33 ft?

[dmcutter]

Isn't that Pascals? And if you have your ascent rate in furlongs per fortnight, I hope you have the sampling rate set in nanoseconds so it will actually give you a reading.

 

[Blackwood]

If you really want to screw with someone's head, try explaining why the 5# of lead ballast only weighs 5# until they jump in the water.

Technically, that 5# weighs more since it's closer to the attracting mass center, though not by much.

 

[fnfalman]

If you suck the fluid into your lungs and your belly, then that inside water will counteract the outside water.

 

[dmcutter]

If you suck the fluid into your lungs and your belly, then that inside water will counteract the outside water.

Okay, now you're cross posting from the "1,000 ways to die" thread.

 

[kwinter]

The OP asked a simple question. Actually, it was simple-minded coming from a diver who should know better. I don't mind the sarcastic answers intended to be funny. But the ones that are half-truths or just plain ignorant bother me a lot.

It's the old "for every action there is an equal and opposite reaction" thing. If you are in 33 ft of water and neutral, and let's assume horizontal so the pressure is equal over your whole area is equal, the column of water over you is exerting 2 atm worth of pressure on you. The water under you is exerting the same 2 atm of pressure, otherwise you would be sinking.

This argument completely ignores buoyancy, which is very different from pressure. If I add air to my wing in your example, all of a sudden the water below me is exerting more pressure than the water above? It must be, because I'm starting to rise.

Your comments about hydrostatic pressure are true, but that's not the entire story. And someone as simple as the OP is just going to be more confused.

 

[ianr33]

Technically, that 5# weighs more since it's closer to the attracting mass center, though not by much.

Surely it will weigh less? If its at the attracting mass centre it would be weightless

 

[dmcutter]

It doesn't ignore buoyancy. I stipulated being neutral. If you add air you effectively increase your volume and decrease your density and become more buoyant. The water pressure in every direction is still the same at any given depth.

 

[boulderjohn]

The OP asked a simple question. Actually, it was simple-minded coming from a diver who should know better.

One of the reasons that we have a Basic Scuba forum, with the name of it in bold green, is so that new and inexperienced divers can come and get answers to questions without fear of ridicule. The pressure issue is not that simple for many people, and too many Basic Scuba questions get shot down by someone with a "you should know this!" posting.

I just skimmed through the OP's posting history, and it appears to me that she was a NAUI student last year, but did not complete the course because she suffered ear damage during the skin diving portion of the course. She indicated in a post a few weeks ago that she was still working on her certification. Perhaps she has finished it by now, but she is clearly still in the beginning phases of scuba instruction and should be able to expect patient answers to any question she asks here.

 

[Blackwood]

Surely it will weigh less? If its at the attracting mass centre it would be weightless

Actually, it would [-]have[/-] approach infinite weight (div by zero) :mooner: