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This is why I love the TV show Mythbusters: they routinely demonstrate how our intuition on these matters is wrong. (A 30-foot fall onto concrete might still k

by nathanb 13y ago

This is why I love the TV show Mythbusters: they routinely demonstrate how our intuition on these matters is wrong. (A 30-foot fall onto concrete might still kill you, but a 300-foot fall into water will definitely kill you. And if the fall onto concrete doesn't kill you, it will be much easier to get you the medical attention you need if you're not floating in San Francisco Bay).

steveax 13y ago
Not to mention when the fall knocks you out, you won't drown on concrete, unlike landing in the water.
Xcelerate 13y ago
Huh, I never saw the Mythbusters show. Why would a 300-foot fall into water definitely kill you? I know the world dive record is 172 feet. And terminal velocity for a human is about 120 mph. I imagine if you make yourself flat for most of the fall you could lower that speed and then right before you hit the water take a "pencil" position. Would you not at least have some chance of surviving that?
- nicholassmith 13y ago
  If you're a diver, or sky diver, or trained you might have the sense to try that, but for the majority your brain is going to be screaming 'oh fuck' when you're half way down.
- nathanb 13y ago
  Water is noncompressible. Maybe the word "definitely" was misused because there's always the possibility for a fluke, but my understanding is that at terminal velocity hitting water is functionally equivalent to hitting concrete. Look up the "hammer drop" episode of Mythbusters if you want to see the long explanation. The second point still stands, though. I'd rather fall onto the concrete, where I could get help quickly and if I knocked myself out but survived I wouldn't drown.
  - glurgh 13y ago
    In a 300 foot fall, you're not reaching the bottom at terminal velocity. Mythbusters have in fact gone over this a few times and the results are a bit different - falling from such a height onto more or less anything is almost certainly lethal. Given equivalent height, even at terminal velocity, you're still slightly better off falling into water.
    - base698 13y ago
      You're still going about 80 mph. Just from memory it's roughly 20 mph/second until you hit 4 seconds where it's reduced to 10 mph/second due to air resistance. The greatest chance you'd have is to impact shallow water with mud. This has saved at least three people, of which there are fairly spectacular Youtube videos.
- chiph 13y ago
  Water is incompressible. So the fall ends up being pretty close to 300 ft. to concrete vs. 30 ft. to concrete. Entering the water toes-first would just mean you have broken legs as well as being dead.
  - peterwwillis 13y ago
    It seems to me the surface tension is the deal-breaker here. When you land feet first, your feet break the surface of the water, which allows for the water to move around the incoming object. You want to minimize distribution of force to only the bottom of the feet. Of course the force exerted on your feet would more than likely break your ankles and possibly your knees/legs, and severely impinge your hip joint. In addition, your head will likely receive an extreme "punch" as it comes into contact with the water. This alone might be enough to knock someone unconscious or kill them, but it depends on their neck, chest, head, body position, etc. So if the mythbusters test were done again, it should definitely not be a really fat pig landing on its side; it should be a skinny dummy landing perfectly straight. I am not a scientist, but I do have experience with cliff diving. (The real trick is when the water level is low, you have to expand your body as soon as you hit the water so you don't shoot down and hit the rocks at the bottom!)
    - jerf 13y ago
      They did some stuff with cliff-style diving too (not quite that high, but it was good enough). That's one of many episodes that convinces me that they play at being more ignorant than they really are in the show, for dramatic purposes; it just isn't plausible that they do enough research to find a guy specialized in high diving, but somehow didn't find out what he could do before he came. I enjoy the show and I enjoy the results, but wish they would be a bit more honest at times, or be a bit more willing to say "Before we start, here's what the 'book' answer to the question is", because it's often obvious they have it. Also, editing makes it hard to tell, but it's pretty clear they very often come prepared with plans B and C to the offsites, again, making it pretty clear that they aren't as surprised that A failed as they play at.
    - maxerickson 13y ago
glurgh 13y ago
Mythbusters: they routinely demonstrate how our intuition on these matters is wrong. Or demonstrate that things we're sure about are sometimes not quite right: http://www.youtube.com/watch?feature=player_detailpage&v=E408JigEcFI#t=298s http://www.youtube.com/watch?feature=player_detailpage&v=E40... (Fast forward to 5 mins) 300-foot fall into water will definitely kill you. Some do survive the actual jump and impact into the bay. Some (very rarely) are even recovered and survive the entire ordeal.
- mapt 13y ago
  About 2% if I recall correctly.
nadrafia 13y ago
Mythbusters busted that myth. Water is preferable to concrete they determined...

by nathanb 13y ago

steveax 13y ago

Not to mention when the fall knocks you out, you won't drown on concrete, unlike landing in the water.

Xcelerate 13y ago

Huh, I never saw the Mythbusters show. Why would a 300-foot fall into water definitely kill you? I know the world dive record is 172 feet. And terminal velocity for a human is about 120 mph. I imagine if you make yourself flat for most of the fall you could lower that speed and then right before you hit the water take a "pencil" position. Would you not at least have some chance of surviving that?

nicholassmith 13y ago
If you're a diver, or sky diver, or trained you might have the sense to try that, but for the majority your brain is going to be screaming 'oh fuck' when you're half way down.
nathanb 13y ago
Water is noncompressible. Maybe the word "definitely" was misused because there's always the possibility for a fluke, but my understanding is that at terminal velocity hitting water is functionally equivalent to hitting concrete. Look up the "hammer drop" episode of Mythbusters if you want to see the long explanation. The second point still stands, though. I'd rather fall onto the concrete, where I could get help quickly and if I knocked myself out but survived I wouldn't drown.
- glurgh 13y ago
  In a 300 foot fall, you're not reaching the bottom at terminal velocity. Mythbusters have in fact gone over this a few times and the results are a bit different - falling from such a height onto more or less anything is almost certainly lethal. Given equivalent height, even at terminal velocity, you're still slightly better off falling into water.
  - base698 13y ago
    You're still going about 80 mph. Just from memory it's roughly 20 mph/second until you hit 4 seconds where it's reduced to 10 mph/second due to air resistance. The greatest chance you'd have is to impact shallow water with mud. This has saved at least three people, of which there are fairly spectacular Youtube videos.
chiph 13y ago
Water is incompressible. So the fall ends up being pretty close to 300 ft. to concrete vs. 30 ft. to concrete. Entering the water toes-first would just mean you have broken legs as well as being dead.
- peterwwillis 13y ago
  It seems to me the surface tension is the deal-breaker here. When you land feet first, your feet break the surface of the water, which allows for the water to move around the incoming object. You want to minimize distribution of force to only the bottom of the feet. Of course the force exerted on your feet would more than likely break your ankles and possibly your knees/legs, and severely impinge your hip joint. In addition, your head will likely receive an extreme "punch" as it comes into contact with the water. This alone might be enough to knock someone unconscious or kill them, but it depends on their neck, chest, head, body position, etc. So if the mythbusters test were done again, it should definitely not be a really fat pig landing on its side; it should be a skinny dummy landing perfectly straight. I am not a scientist, but I do have experience with cliff diving. (The real trick is when the water level is low, you have to expand your body as soon as you hit the water so you don't shoot down and hit the rocks at the bottom!)
  - jerf 13y ago
    They did some stuff with cliff-style diving too (not quite that high, but it was good enough). That's one of many episodes that convinces me that they play at being more ignorant than they really are in the show, for dramatic purposes; it just isn't plausible that they do enough research to find a guy specialized in high diving, but somehow didn't find out what he could do before he came. I enjoy the show and I enjoy the results, but wish they would be a bit more honest at times, or be a bit more willing to say "Before we start, here's what the 'book' answer to the question is", because it's often obvious they have it. Also, editing makes it hard to tell, but it's pretty clear they very often come prepared with plans B and C to the offsites, again, making it pretty clear that they aren't as surprised that A failed as they play at.
  - maxerickson 13y ago

glurgh 13y ago

Mythbusters: they routinely demonstrate how our intuition on these matters is wrong. Or demonstrate that things we're sure about are sometimes not quite right: http://www.youtube.com/watch?feature=player_detailpage&v=E408JigEcFI#t=298s http://www.youtube.com/watch?feature=player_detailpage&v=E40... (Fast forward to 5 mins) 300-foot fall into water will definitely kill you. Some do survive the actual jump and impact into the bay. Some (very rarely) are even recovered and survive the entire ordeal.

mapt 13y ago
About 2% if I recall correctly.

nadrafia 13y ago

Mythbusters busted that myth. Water is preferable to concrete they determined...