flamingknives Posted June 27, 2005 Share Posted June 27, 2005 I realise that the density of snow varies - 0.1 to 0.5 g/cc is an enormous variation. Snow is never more dense than water - even solid ice is less dense than water What yuvuphys' equation doesn't take into account is the mechanical strength of the snow, which in most cases would be fair for fallen snow, rather than that packed into place. 0 Quote Link to comment Share on other sites More sharing options...
Dandelion Posted June 27, 2005 Share Posted June 27, 2005 Originally posted by flamingknives: Using consistant units and the same values, bar the density, I get 3.93m of snow from that equation. Hey, that's almost the same figure as I got, though I omitted dispersing the weight over the area of the falling man and got a higher figure. I feel so...engineer-ish. Cool. Anyway back to business, holding Flames and Yuv in the arm preventing them from fleeing, we remain at the last and critical question. Assuming a human body decelerating at those speeds (from 22 m/s to zero in 3.93m or 0.79m - assuming the complex dynamics of snow would land us someplace in between), would the G itself damage the person? - Paul, even living in Scandinavia these days, most of the snow I experience is the black, sooty variant that covers urban areas. Snowcovers even in these freezing Northern wastes posing as a nation rarely reach the metre on average - but as you say, in a modern society that could easily knock out traffic, electricity and other infrastructure. I have experienced powdersnow in the Alps though, have had it blow in my face like dust and the top 30-40cm ground cover being like walking in flour or lightweight sand really. Very arduous going. Snowlayers will follow a complex circle with freeze and refreeze in uneven layers, then compress itself unevenly, leaving us with a very varying degree of porosity (casuing avalanches too). You can have powdersnow for 20cm resting on a layer of tightly packed wet snow, making you slip all the time. Most arduous of all was when the topsnow started to melt on a sunny day, decresing porosity, then froze during the night creating a semi-ice toplayer next day. Arduous to walk in, and you'd cut your calfs in it. I am not totally alien to the idea of a person falling out of a plane and surviving when landing in snow. Like you I have a problem imagining what type of depth that would require IRL. Of course, I can also imagine what will happend if the guy is not in a perfect crucifix position, perfectly horizontal, when he lands. Even so, the guy simply has to be totally knocked out, must be a bit like being in a car accident or something. I imagine. I am trying to remember any alpinists falling in snow and surviving, but I guess they tend to hit rocks as they go down anyway. Cheers Dandelion 0 Quote Link to comment Share on other sites More sharing options...
flamingknives Posted June 27, 2005 Share Posted June 27, 2005 Originally posted by some bloke: 25g is a good figure for human resiliance to acceleration. Up to this acceleration the chance of injury is low. Survival is likely up to 60 g. This is assuming a reasonable level of support. A body travelling at 50mph (22.2m/s), decelerated at 25g will come to rest in the space of 1m. It will require a decellerative force of 19620N distributed over the body surface. (2 metric tons) Thus, coming to rest in less than 1 m will run the risk of injury. Of course, 25G as a figure is based on a decent level of support to the body and the acceleration pushing from behind or below into the trunk. Accelerations pushing sideways or from the front have lower acceptable G limits. (10 to 15 G) The distance required to slow them to a halt at a given acceleration is a linear relationship, so for 10G it would need 2.5m. The figures using Yuvuphys' equation are based on a 60mph (26.667m/s) initial velocity. As a final caveat, it's possible to fall badly at any speed, as any jitsuka will attest. 0 Quote Link to comment Share on other sites More sharing options...
Dandelion Posted June 27, 2005 Share Posted June 27, 2005 Jitsuka? Who is Jitsuka? Thanks Flames. That settles it then I think, even a one metre layer of snow provides a fair chance of survival, albeit not without injury. And we need to recall Johns provided lines of "I certainly wouldn't" etc. Cheerio Dandelion 0 Quote Link to comment Share on other sites More sharing options...
flamingknives Posted June 27, 2005 Share Posted June 27, 2005 Jitsuka - someone who practises Ju Jitsu, a martial art concentrating on locks and throws. You fall a lot. And yes, diving into a snowdrift from an airborne 'plane is certainly not something I'd do out of choice. 0 Quote Link to comment Share on other sites More sharing options...
jacobs_ladder2 Posted June 27, 2005 Share Posted June 27, 2005 Numbers. If they weren't the basis of reality I would deny their existence like I do bad music. Cheers Paul 0 Quote Link to comment Share on other sites More sharing options...
flamingknives Posted June 27, 2005 Share Posted June 27, 2005 Ah, but they are not the basis of reality, they're just very useful in describing and predicting it. 0 Quote Link to comment Share on other sites More sharing options...
jacobs_ladder2 Posted June 28, 2005 Share Posted June 28, 2005 Originally posted by flamingknives: Ah, but they are not the basis of reality, they're just very useful in describing and predicting it. That, my friend, is an invitation to get really off-topic. Paul 0 Quote Link to comment Share on other sites More sharing options...
flamingknives Posted June 28, 2005 Share Posted June 28, 2005 hmm? Or rather, hmm? [ June 28, 2005, 10:05 AM: Message edited by: flamingknives ] 0 Quote Link to comment Share on other sites More sharing options...
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