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Thread: How can we survive free fall from height?

  1. #1 How can we survive free fall from height? 
    Forum Sophomore Hymenophyllum's Avatar
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    How can we survive free fall from height? What are the limits?


    He is numb from his toes down
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    Genius Duck Moderator Dywyddyr's Avatar
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    You ALWAYS survive free fall. From ANY height.
    It's hitting the ground that kills you.


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  4. #3  
    Forum Sophomore Hymenophyllum's Avatar
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    I mean 'drop' ofc.
    He is numb from his toes down
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    Forum Radioactive Isotope cosmictraveler's Avatar
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    Parachutes would be helpful. Then again just don't jump off any high places to begin with.
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  6. #5  
    Forum Cosmic Wizard
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    "A few people have survived a fall of thousands of feet without a working parachute. This research page is dedicated to recording their stories."

    The Free Fall Research Page, sponsored by Green Harbor Publications
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  7. #6  
    Forum Cosmic Wizard
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    Quote Originally Posted by Hymenophyllum View Post
    How can we survive free fall from height? What are the limits?
    I've survived free falls from 35,000 feet!
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  8. #7  
    Cooking Something Good MacGyver1968's Avatar
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    I've heard there is a technique they teach in the military called "break fall"...where you slap the ground with your arms and legs at just the right moment before impact, and it will slow you down slightly. I'm not sure if this is true or works.
    Fixin' shit that ain't broke.
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  9. #8  
    Anti-Crank AlexG's Avatar
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    Mac, that works when you're thrown in hand to hand combat. It's not effective when falling thousands of feet.

    The best way to survive is to land on something yielding. There was a case in WWII where a belly gunner on a B-29 fell 26000 feet and survived relatively unscathed by landing on a haystack.

    Just recently, there was a skydiver who's chutes failed to deploy who survived by landing in a large patch of brambles.

    It is however, the exception, rather than the rule.
    Its the way nature is!
    If you dont like it, go somewhere else....
    To another universe, where the rules are simpler
    Philosophically more pleasing, more psychologically easy
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    Cooking Something Good MacGyver1968's Avatar
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    That makes sense, alex. Thats why I included the disclaimer. If your traveling at terminal velocity, slapping the ground ain't gonna help. It MIGHT slow you down .05% if you timed it perfectly....but the end result is still the same....pancaked Mitch.
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  11. #10  
    Cooking Something Good MacGyver1968's Avatar
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    Ok....I have a question about falling into water. You can safely fall into water from a reasonable height, but at a certain point, it can become fatal....Like when people jump off the golden gate bridge to commit suicide. What is the mechanism that causes this? Is it that you are traveling too fast to break the surface tension of the water quickly enough or what?
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  12. #11  
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    Quote Originally Posted by MacGyver1968 View Post
    What is the mechanism that causes this? Is it that you are traveling too fast to break the surface tension of the water quickly enough or what?
    Simple deceleration. You break your ribs, spine, rupture your aorta etc due to the hundreds of G's you see slowing down from air terminal velocity to water terminal velocity in a few feet.
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  13. #12  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by MacGyver1968 View Post
    Ok....I have a question about falling into water. You can safely fall into water from a reasonable height, but at a certain point, it can become fatal....Like when people jump off the golden gate bridge to commit suicide. What is the mechanism that causes this? Is it that you are traveling too fast to break the surface tension of the water quickly enough or what?
    Oh dear!
    We had this one a couple of years on *cough* the other science forum, and I ended up doing a lot of calculations (and inventing a new term 1).
    I think it was a thread started by Inzomnia (or her revamped name Edit- no it wasn't Inny) asking exactly that.
    It wasn't the surface tension so much as the fact that the compressibility of water and its ability to "move out of the way" caused it act "like a solid" above certain speeds from what I remember.
    (Just done a quick couple of searches and they failed totally. And then... brainwave - Google it! Here ya go Mac: Water as unyielding as concrete).
    Um... YOU posted in that thread Mac. Is age affecting your memory?

    1 IIRC it was "squishability value". Yep.
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  14. #13  
    Cooking Something Good MacGyver1968's Avatar
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    Dude...I don't even remember what I had for breakfast.
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  15. #14  
    Forum Professor Zwolver's Avatar
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    Quote Originally Posted by MacGyver1968 View Post
    Ok....I have a question about falling into water. You can safely fall into water from a reasonable height, but at a certain point, it can become fatal....Like when people jump off the golden gate bridge to commit suicide. What is the mechanism that causes this? Is it that you are traveling too fast to break the surface tension of the water quickly enough or what?
    Dywyddyr has given a link to it, but an addition to that.

    When dropping in water, the initial impact is great, but not comparable to concrete. Water does absorb about half of the energy from the initial hit, which may kill you instantly, but that is not all. Water splashes up, and when water passes your body at 300m/s, it tends to cut like knives. At those speeds, water will act like a metal french fry cutter. You basically end up, sliced in parts, or paste when dropping from that height. But no worries, you won't survive the fall anyway.
    Growing up, i marveled at star-trek's science, and ignored the perfect society. Now, i try to ignore their science, and marvel at the society.

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    I've heard hypothetically if you were to drop a rock or some large object to break the surface tension of the water just before you hit, you can survive.

    I'm still interested to hear how people have survived falling on land.
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  17. #16  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by robj37 View Post
    I've heard hypothetically if you were to drop a rock or some large object to break the surface tension of the water just before you hit, you can survive.
    If I remember correctly Mythbusters completely disproved that claim.
    (It's not surface tension that causes the damage anyway, take a look at the thread referenced in post #12).
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    Depends how you fall and from where, I guess.
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  19. #18  
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    Quote Originally Posted by robj37 View Post
    I've heard hypothetically if you were to drop a rock or some large object to break the surface tension of the water just before you hit, you can survive.
    It helps, but not because it "breaks the surface tension" - but because it physically moves water out of the way. A large enough object, traveling fast enough, will bore a hole in the water which will then try to fill back in, with the water displacing the air in the process. If you hit very shortly after the object hits, you will be hitting a column of water mixed with air, and that will result in much lower deceleration forces on your body.

    There are several ways of creating a 'column' of gas/water mixture, and these methods can greatly reduce deceleration forces on objects hitting the water.
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  20. #19  
    Forum Radioactive Isotope skeptic's Avatar
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    If you 'spreadeagle' as you fall, it reduces your falling velocity. You will still be killed instantly most of the time on impact. But the spreadagle position may increase your chances of a fluke landing. In WWII there was a guy who bailed out of a burning plane over Germany with no parachute, he spreadeagled, and hit a pine tree a glancing blow, which slowed him further, then fell into a snow drift and survived. Any survival is a fluke, but you can increase your chances of a fluke from maybe a million to 1 to a thousand to 1 against.
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  21. #20  
    Forum Ph.D.
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    It aint the fall that hurts, its the sudden stop.
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  22. #21  
    Genius Duck Moderator Dywyddyr's Avatar
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    Quote Originally Posted by skeptic View Post
    but you can increase your chances of a fluke from maybe a million to 1 to a thousand to 1 against.
    But, as Terry Pratchett pointed out: million to one shots happen nine times out of ten.
    "[Dywyddyr] makes a grumpy bastard like me seem like a happy go lucky scamp" - PhDemon
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