# Lethality of jumping into shallow water from height

Discussion in 'Physics & Math' started by MJP, Mar 7, 2018.

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## Would they survive?

1. ### MJPRegistered Member

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Wondering how survivable it would be to dive 30m into shallow water (say 1m) for the average adult.

Guessing that age and physique/fitness would affect likely outcomes. So let's assume a 20-30 year old weighing 110lb. How about if thy weighed 170lb with that being more flab?

Also guessing the area landed on would affect things but don't know how well the average person could control how they'd land in that situation either. Obviously landing the head would be horrendous, but what about landing on their back?

Could someone maintain a pencil dive head first without training for that distance? Is a feet first pencil dive easier to hold form on?

So many variables, it's fascinating. Thanks.

3. ### Gawdzilla SamaValued Senior Member

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People have survived jumps from the Golden Gate and Brooklyn Bridge without being trained divers. I suspect their form on entering the water was less than perfect, especially if they had changed their mind on the way down.

5. ### DaveC426913Valued Senior Member

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Both those water bodies are considerably deeper than 1m.

7. ### MusikaLast in SpaceValued Senior Member

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Last edited: Mar 7, 2018
8. ### Gawdzilla SamaValued Senior Member

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But did the jumper penetrate deeper than one meter?

9. ### MJPRegistered Member

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Diving does seem to result in penetrating the water at least a few feet so probably more than a metre or two even from low heights see https://www.thoughtco.com/water-depth-and-safe-diving-1100176 that’s why I’m wondering how dangerous diving into shallow water would be for most people because of hitting the bottom of the water causing injuries, just don’t know how bad those injuries could be and what kind of recovery from them would be, especially if the water is outdoors and may have rocks and stuff in it. Don’t know what safety precautions could minimise that either.

Gold gate bridge deaths could be from the height/impact or from drowning after impact given how deep it is iirc, so a dive from a lower height wouldn’t have as much impact force but if the water is shallower and has rocks or gravel there could be minor or major injuries but I don’t know how lethal it could be and not comfortable about trying to find out through trial and error!

10. ### Gawdzilla SamaValued Senior Member

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Oh, go jump into San Francisco Bay.

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Huh?!?

12. ### Gawdzilla SamaValued Senior Member

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Just funnin' ya. No offense meant.

13. ### sideshowbobSorry, wrong number.Valued Senior Member

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All of the above. You'd need a lot of data to determine the number of dead, the number of vegetables, etc. It would be hard to get enough volunteers for the experiment.

14. ### Gawdzilla SamaValued Senior Member

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We could tell the right that the left is against jumping off bridges...

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15. ### SeattleValued Senior Member

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How stupid is this scenario? Jumping into 3 feet of water from 90 feet? That would be waist deep water for me and 90 feet would essentially be like a 9 story building. The water is going to do very little so 3 feet is ridiculous.

Of course they would die. What 20 year old weighs only 110 lbs? A woman? What woman is stupid enough for this scenario?

The water needs to be deeper for it to have much effect. After a certain height though, the depth isn't as important because the impact with the water would cause instant death due to incomprehensibility.

16. ### DaveC426913Valued Senior Member

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Death by confusion.

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17. ### sideshowbobSorry, wrong number.Valued Senior Member

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I read an article once about aircraft accidents. It said that female pilots tended to have accidents because of inexperience (with weather conditions, etc.) while male pilots tended to have accidents because they tried to make the aircraft do something it couldn't do. If a woman falls 90 feet into 3 feet of water, it may be because she's new at rock climbing. If a man does, it's likely to because he said, "Hey guys, look what I can do!"

18. ### iceauraValued Senior Member

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So a SE Asian or SA Indio girl, maybe a gymnast. That opens up some possibilities for entry control etc.
Although I doubt total mass would be key - gravity operates on every ounce alike.
At least one of the people who have survived terminal velocity falls - out of airplanes without parachutes, etc - fell into the ocean.
No word on whether their ability to comprehend the situation was a key factor.

19. ### SeattleValued Senior Member

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That does tell us anything however since there are some people who have done the same thing and hit land have still survived. It's not something I would count on however.

20. ### SeattleValued Senior Member

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That should be "incompressibility". Thanks for the catch.

21. ### nebelValued Senior Member

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I jumped from the 10 meter tower once, over rotated and landed partially on the back, survivable. I fell in my house from a scaffolding sabotaged by my son from ~ 18 feet head heights onto a hardwood floor, feet 13 feet with no ill effects, because I fell partially forward, energy dispersed not into a crunch but forward movement.
These feats of going into shallow water could be based on that energy dispersal method, soft medium, used to convert vertical velocity into horizontal movement.
10 meters? never again. just looking down is enough to scare me now.

22. ### nebelValued Senior Member

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is there not an US airman in WW2 that survived a jump from 5000 feet without a parachute?

23. ### RainbowSingularityValued Senior Member

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20 to 30 yo weighing 50 kilos would be a very light female, small frame or borderline under wieght.
ave height is around 5'6 or 165 cm's
soo 50 kgs is borderline
given the height of the person at 1.65 meters
note your top weight is only 78kgs... which is obviousely not an USA person as the average usa person is obese and closer to 95 kgs (210lbs to 250lbs) (which the volumetric impact of the fluid to fluid of a 250lbs person on to water surface would be equal to a high speed car accident which has only a 15% to 20% survivability rate... roughly.

the total body of the person can not enter the water prior to hitting the bottom.
if they land feet first, then its like rolling a dice as the bones fracture and stab up through the body causing multiple injures cutting internal organs and puncturing lungs or cutting majour arterys.
the neck impact may be enough to knock them out, break their neck and thus render them unconscious under water... which is generaly quite fatal.

if they landed on a perfect angle(what ever that would be) with broken water surface, they might survive if they were rescued immediately on hitting the water.

Last edited: Mar 12, 2018