I just saw a video of trout being dropped from an airplane to stock mountain lakes.
So I was thinking, if I was suspended in water (let’s say I was in the middle of a 4m di. water balloon), and I was dropped from an airplane (let’s say 50m above the water), would being suspended in water help ease the impact of hitting the water? Or would it be more like a water balloon hitting concrete?
In: Physics
It would be like a water balloon hitting concrete.
Water is incompressible, so when the balloon hits the water, the internal water would transmit the impact forces to your body almost immediately. This means you would still experience a very high force of impact.
Hitting water at high speeds can be similar to hitting a solid surface because of surface tension and the incompressible nature of water. The high impact velocity would make the water’s surface behave more like a solid for an instant.
The water inside the balloon would distribute the impact forces around your body, potentially mitigating some localized injuries (like breaking a limb), but not enough to avoid serious trauma.
Since water isn’t compressible, when it hits, there’s going to be a pressure shock wave through the water. Neither the landing pool nor the dropped ball of water want to give, but the water ball has the option of spreading out horizontally. But it’s being forced to by the impact and that’s going to produce a compression pressure inside the water as it hits.
Your falling ball of water is going to apply a crushing force on whatever is inside it. Mythbusters showed that fish aren’t tolerant of those kinds of pressure shocks – if you fired a bullet into a barrel with fish in it, you will kill fish without even hitting them. Bullets may be fast, but 4m diameter water balloon is HEAVY – 1 cubic meter of water is 1 ton by definition. That much water being forced to change direction on impact crushing the fish… it would be totally lethal for any decent fall.
4m of water isn’t much. The water balloon will deform the water you drop it into, and maybe reduce the acceleration. But slowing it from 0m to 2m after a fall of 50m isn’t much. A 10m balloon would weigh enough that it makes a better dent in the water you drop it into.
As always, there is an [XKCD](https://what-if.xkcd.com/12/) for this. About halfway down, it discusses how you would be crushed to death if you fell inside a giant globe of water.
No, it will suck *way* more. Water will distribute the shock (more) evenly, to make sure that what was supposed to be broken legs, is also damaged neck and spine, months of headache, swollen fingers and so on. Even if your legs get a bit *less* broken. That’s why underwater explosions are more dangerous than ones on the land and why demolitionists use stuff like shaving cream to direct the blast.
Less direct trauma from fall, more overall horror.
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