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Author Topic: Would the lethal G-Force acceleration be the same for a fish and a mouse?  (Read 1767 times)

Offline CliffordK

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I was just thinking today.

How would a fish respond to high G-Force acceleration?
Would it be different than a mouse, rat, or for that matter a human?
A Dolphin?

In particular, would the lethal G-Force be the same?

This would, of course, be in a tank of water.


 

Offline imatfaal

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I think the mouse would drown.

Acceleration is dangerous in two (at least) scales - the method it is imparted to the body and the differential effect on body parts. 

If I am standing on a platform that is suddenly jerked upwards taking acceleration to 100g then my head would crush my uprising neck, my head and torso would crack my uprising hips, etc.  If I were cushioned by being supported completely in water some effects might be ameliorated and I could stand a higher acceleration than standing up (not 100g though I would hazard).  There is also the problem that my heart would have to work many times harder to pump the blood the foot and a bit to my brain, and for the returning blood in the veins draining the lower body to get to the heart.  This would not be helped by being well supported - although being horizontal might help. 

 

Offline CliffordK

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The question about the fish was...

If one is embedded in a liquid with equal density as the organism, then it would give excellent external support for the body.

However, if one thinks of it as centrifuging.  Then, there could be a problem with separating everything inside of the organism by density.  So, air and oils would move upward, and higher density compounds would move downward.

Reclined, or even flat on one's back is probably best, with a good conforming support (like water), or possibly a custom moulded surface (with some padding).  Anyway, so an aquatic environment like for a  fish might still rank as quite good.

For short acceleration (a few minutes), then one wouldn't have to worry about leg perfusion.  In fact, a pressure suit might be designed to push blood out of the legs and possibly the arms.  Or, one could design an external leg pump that would regularly compress and relieve pressure on the legs to assist the heart.  An "Iron Lung"?

I'm doubting that we could develop a technology to sustain high acceleration (other than a centrifuge) for more than a few minutes, or perhaps a few hours.
« Last Edit: 29/09/2012 20:41:33 by CliffordK »
 

Offline Bored chemist

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As has been pointed out, the problem is tissues with different densities so a fish with a swim bladder or a dolphin with lungs has a problem as the air filled bits are forced "upwards" while the rest of the body moves "down". I suspect that a swim bladder is a lot less fragile than lung tissue so the fish would do better.
And earthworm with no dense skeleton and no airspaces (I think) would be even better placed to survive high G.
 

Offline evan_au

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So one of the more rugged multi-cellular organisms would be a jellyfish: All its body parts are approximately neutral density in their native water habitat. There are no internal organs of different density (like swim bladders or lungs) that could be torn off by the acceleration.
[In contrast, the Portuguese Man-of-war would not be very rugged, since it has an air-filled sail which floats above the waterline: http://en.wikipedia.org/wiki/Portuguese_man-of-war]

Single-celled organisms are probably more rugged than multi-cellular organisms, since their internal circulation has a much smaller extent, and will be exposed to much less differential pressure.
« Last Edit: 30/09/2012 11:18:39 by evan_au »
 

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