What is the effect on gravity underwater?

[Walter]

If the circulatory system had large spaces full of air, this would be valid. However, it does not. It's entirely incompressible liquid and is surrounded by incompressible, highly flexible tissue.

That was my point. Neither analogy is valid. Neither imitates the conditions in the body. I think you are making way too many assumptions. While I have an idea of what would actually happen, I'm aware I won't know without an experiment. You seem to believe you can determine the outcome without actual evidence. No offense, but you sound like Aristotle.

 

[novadiver]

so , still no scientific evidence proving me wrong. interesting

 

[novadiver]

That was my point. Neither analogy is valid. Neither imitates the conditions in the body. I think you are making way too many assumptions. While I have an idea of what would actually happen, I'm aware I won't know without an experiment. You seem to believe you can determine the outcome without actual evidence. No offense, but you sound like Aristotle.

hey Walter, there's only one "source" of info for some, and it has nothing to do with science or physics, I'm suprised that no-one brought up the effects of wetsuit squeeze to counterbalance the bends

 

[JimC]

so , still no scientific evidence proving me wrong. interesting

Or proving you right.

 

[jonnythan]

hey Walter, there's only one "source" of info for some, and it has nothing to do with science or physics, I'm suprised that no-one brought up the effects of wetsuit squeeze to counterbalance the bends

You're right.

I confess.

I learned all the physics and physiology I know from GUE

 

[simbrooks]

Ok, so these guys seem to agree that blood finds it harder to flow to your feet than head if UW being vertical head up here. Now surely if you stopped the pumping effect of the heart to overcome that the pressure would distribute the blood according to its SG which would make it slightly negative compared to the rest of the body (at least the liquid and solid parts) and the body of water - water would fill the air cavities (assuming the air could escape) eventually so why wouldnt the blood eventually "sink" within the body?

Has anyone even consulted any references on physiology here? I will check mine tonight... i found nothing in the US Navy publications on a quick skim through the pdf copy i have.

 

[jonnythan]

Also, it's the same idea as fighter pilots who wear special flight suits that squeeze their lower extremeties whe pulling high G's. The external pressure prevents the blood from pooling below.

 

[Mako Mark]

Ecaxtly Unless you don't have enough blood in your alcohol. In which case you shouldn't dive with Ziploc bags anyway. Umm.

:lol:

" We know that happens in response to weightlessness, because over long periods of time in a weightless environment, greater than (otherwise) expected dehydration and cardiovascular degeneration have been observed in astronauts.

Thankyou sterling..

Im with Jonnythan on this one Walter, even if you dont quite get his metaphores. The human response to immersion in water is a raising of the arterial blood pressure due to the lack of work to counter the hydrostatic head between the heart and the head caused by gravitational pull on the blood while the body is not immersed..

And archemedies principle still stands when you consider air as the (liquid) medium. Take Jonnythans ziplock bag and poke a hole in it with an urchin spine, the liquid will fall quickly to the ground.

Do the same underwater and the liquid will leak out but not fall to the bottom of the water column.

I'd like to see some sort of study on whether being vertical or horizontal in the water can increase or decrease bubble formation or affect offgassing in any way.
.

My guess is that a 6 ft change in depth of the blood circulating rapidly through the body while vertical, should produce more micro bubbles than if the same blood is pumping horizontally and not experiencing the same 6 ft change in absolute pressure.

Just move a soda rapidly up and down and see if you get a more rapid offgassing when you open it.

 

[WarmWaterDiver]

As far as the topic in the original post goes,

Gravity is inversely proportional to the square of the distance between the TWO bodies / objects involved. So, the discussion really needs to be framed relative to elevation, such as sea level, rather than just any water. The lower you go below sea level, the greater the force of gravity relative to being at sea level - and vice versa. But, unless there is a pretty great relative distance for us 1 to 3 meter tall humanss involved, like the space shuttle flying, it's pretty much negiligible. I don't think I've read of a body of water discovered deep enough to significantly change the gravitational force relative to sea level.

Jonnythan, can you dredge up the general formula relating gravity vs distance between two objects for us? It's been a long week at work and I'm not up to prying in reference books this evening.

 

[simbrooks]

F=G.ma.mb/r^2

Not so hot with formatting the text, but:
F = Grav force
G = Grav const
"ma" or "mb" = masses of objects (a and b)
r = distance between the objects.

Our mass vs the Earth's mass is quite negligible, therefore only r can really effect the amount of grav force we feel - as you correctly stated