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Falling 47 stories

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My physics absolutely stinks, mostly when it comes to the absolute basics.

 

So anyways, there was this guy who survived a 47 story fall, onto the PAVEMENT. Splat. When someone/something is falling, do they keep accelerating as they fall further and further, or do they reach a maximum speed? Does someone who falls 90 stories have similar chances of surviving to someone who falls 47 stories? I've read about people surviving falls out of airplanes, so something tells me that I am right, but I am not sure.

 

They had to pump almost twice his normal blood volume back into him. What a mess.

 

http://news.yahoo.com/s/ap/20080104/ap_on_he_me/skyscraper_fall_survivor

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They do reach a maximum speed. There is a constant force of gravity acting on them, which would accelerate them faster and faster, but there is also the opposite force of wind resistance, which increases the faster you're going. Eventually, the force of wind resistance will equal the force of gravity, and so you'll have no net force, and so you'll stop accelerating.

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It's called terminal velocity. The question becomes, is 47 stories enough to reach terminal velocity? Well, it depends on how much wind resistence was acting on the guy who was falling.

 

 

I think the more interesting question is how somebody can survive the negative acceleration of coming to a full stop when hitting the pavement. Zoinks! :D

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You'll hit terminal speed, of ~120 mph (depending on your mass and surface area) at some point. Since drag depends on speed squared, your acceleration will rapidly diminish, so 90 stories would give you about the same speed as 47.

 

There my be some stats out there from accidental falls and suicide attempts that would tell you the probability of surviving a jump or fall from a certain height, and it should flatten out at some point, at slightly above zero. (A few people have survived parachute-less jumps from planes.). I have a vague recollection of such information; there's a threshold where you get injuries and few deaths, and then transition into mostly deaths. But I can't find anything relevant at the moment.

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This is really interesting! Does this mean that you in theory can fall and survive from ANY height if the conditions were the same as on earth?

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That's really awesome in my opinion! I LOVE the laws of physics :D

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I'd say it as: your odds of dying don't noticably increase with height after a certain point. Not that they can increase much ...

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This is really interesting! Does this mean that you in theory can fall and survive from ANY height if the conditions were the same as on earth?

 

Yes.

As iNow stated, you can survive falling from just about any height.

However, after the fall, where the velocity abruptly returns to zero, can be very very hazardous to your health.

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well, if your falling from over about 5 km (15000ft) you could very well die before you hit the ground from a mixture of hypoxia and the extreme cold. going higher makes this more likely. eventually you'd get t an altitude where you'd burn up on reentry as well.

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