Assume a human was allowed to freely fall from the top of the atmosphere under the influence of gravity. Tell me what will happen during his descent 1) Will he be burnt to ashes before he reaches the ground on account of friction with the air just like meteorites are. 2) Will he actually reach the surface and die due to impact with the ground. 3) Is there a possibility however slim that he may survive? While we are at it also can any of you tell me what is the maximum height a human has survived a free fall assume no parachutes or the like. This should be interesting
Here, check this out http://www.redorbit.com/news/space/1402000/adventurer_plans_to_parachute_from_space/
One small point: meteorites don't burn up before they reach the ground. By definition it's not a meteorite until it actually survives the fall and hits the ground.
He would probably suffocate or die of exposure to the cold. If he wasn't in orbit, then he wasn't travelling fast enough for friction to be a problem. He would accelerate to the maximum speed rather quickly, but that's less than 300mph.
Even if he dies what becomes of his body? Will it reach the surface intact and then splat or will he be vaporized due to friction with atmosphere?
Well presumably the guy planning the free-fall from X zillion miles up isn't also planning on burning up in the atmosphere, so the answer would appear to be "no, he won't vaporise". Meteors burn up because they enter the atmosphere already with a much higher velocity than simply free fall.
Yes. According to the link he'll reach over Mach 1 at high altitude, and lest you think that's simply a function of reduced air pressure = lower local speed of sound = reduced actual speed it also says he'll maybe hit 1,000 mph! But his speed will drop as he encounters gradually increasing air pressure.
I imagined so but it seemed almost too simple. Mach 1? Could be a blast. I wonder what the pressure change would feel like as a zero-trajectory ballistic object.
You wouldn't enjoy it. At Mach one there would be significant heating. Not enough to vaporize, more like flash frying. Please Register or Log in to view the hidden image! My sister's father in law was a 747 pilot for United. Even a jumbo's cruising speed (iirc about M 0.6) is fast enough to raise the leading edges to hot enough to burn your hand.
Not necessarily - the heating would be a function of air density (as would the actual speed of sound). Presumably (as previously stated) the guy is planning on surviving the jump so he's checked the temperatures likely to be achieved. That would be because of sustained friction heating and the metal structure/ skin retaining the heat - the guy will hit Mach 1+ for a very short period in very thin air. I'd imagine* that friction heating wouldn't even raise the stagnation layer to body heat. * Wild guess I admit, it's getting on for 6 AM and I can't be arsed to even start looking at calculating it. Please Register or Log in to view the hidden image!
Initially he (or she) will accelerate to a very high speed. As he falls into denser air, friction will slow him down progressively, until near the ground he will have a terminal velocity of a few hundred metres per second. He is unlikely to be heated sufficiently to burn. On impact, he will probably die if he has not used a parachute, although there have been cases where people have survived high falls (e.g. out of aircraft) by landing on "soft" surfaces such as snow or trees or even a railway station roof. The maximum recorded height for a survived fall of that kind of probably a few kilometres, but extra height really doesn't make any difference once you get beyond the height where you're travelling at terminal velocity.
Good point about terminal velocity I forgot about it completely. Now can you tell me what is the minimum height from which he should fall to the ground so that he has acquired terminal velocity and what would be the value of that terminal velocity. Can he survive if he hits the ground with terminal velocity?
Terminal velocity is around 54 m/sec (~120 mph) for a human, requiring a fall from about 148 metres. And survival depends on the type of ground, as indicated in James R's post, mostly unlikely.
1) No. 2) a) yes, they reach the surface; b) yes, they usually die on impact. 3) yes, there are two cases I know of; there was an English bomber crew-member who fell from 22,000 feet without a parachute--it had caught fire and burnt, and when he pulled the rip-cord it came away in his hand. He landed in a deep snowdrift and broke his ankle. When the Germans caught him, he told them of his fall, and they didn't believe him until they took him back there and showed them the big hole in the snow where he landed. The second case involves an air hostess from a Yugoslav Airlines flight which was sabotaged about 30 years ago; she fell 34,000 feet while still strapped in her seat, in the rear section of the aircraft, and landed in a river, IIRR. She survived, but with very serious injuries.
Joseph Kittinger has the record for highest jump & longest free fall. For Project Excelsior, his final jump was from 102,800ft. He claims he broke the sound barrier (others backed him up) and at that altitude, he may well have. He was officially clocked at 614mph. http://en.wikipedia.org/wiki/Joseph_Kittinger To answer your last question, why does someone die in a slip & fall accident and someone else survive a 500ft drop? You should die upon impact with the ground, but others have survived when the rest have died.
No is the short answer. It depends on mass and presented surface area/ shape - which affects resistance to motion through the air. Here and here are useful, especially the latter - there's an on-line calculator (provided you know the drag coefficient of whatever it that's falling). Please Register or Log in to view the hidden image! A human will fall much faster* going head first (although apparently that's not a stable position). * 321 mph according to this...
