I failed all my science courses, I don’t understand much about science but why doesn’t the water just… move like when you jump in normally?
In: Planetary Science
Water is heavy, and all that water has a lot of inertia. When you impact it at high enough speed the water can’t get out of the way fast enough so it’s like colliding with something solid. It will eventually move out of the way, but not before you are injured.
In some cases of high jumps into water, an explosive is set off underwater, creating gas bubbles right before the person or object hits the water. This is done because gas is easier to move through(think like walking in the open air versus walking in water, and this is a sort of in-between)
And water is so hard to move through, that if you fall onto it at high speed, you have to take up all that force you would when normally moving through, just much, MUCH faster and with a LOT more power.
Go to a pool and slap the water as hard as you can with an open hand. See how much it hurts.
When you jump from a big height and hit water, it feels hard like concrete because you’re falling fast. The water doesn’t have time to move out of the way like it does when you jump in normally. So, it can feel really tough when you land.
Very simply put, liquids do not compress. They only displace. That is the theory behind hydraulics.
It does move, but not fast enough.
Imagine you need to push a car (in neutral)
Option 1: stand behind the car and slowly push it
Option 2: sprint as fast as you can towards the car and hit it
I think you know what will happen in option 2.
Water needs time to move and get out of the way. It doesn’t compress like a spring and dampen your fall, all it does is simply get pushed away from the object entering it.
At a certain height, you’re falling with enough speed that the water simply cannot get out of the way fast enough.
The smaller the surface area hitting the water, the faster said object can enter the water safely because you need to displace less water. So when you belly flop into a pool from the side, it hurts like hell. It’s also why divers can jump with hands or feet first from greater heights and higher speeds and be fine.
Water is not “soft” relative to you. Jumping into water is a bit like a head-on car crash.
Water is heavy – it doesn’t want to move easily. It’s actually as heavy as you – you’re mostly water yourself anyway, so you’ve very similar density (most people are actually slightly less dense than water). So the water is trying to push you out of the way as hard as you’re trying to push it. Yes, you have a bit more structure, so you can break an entry with the hard bits of your body such as your feet up to a point – but the water IS still resisting, so that ONLY works up to a point – and above quite small heights, if you hit even slightly wrong, you’re going to squish almost as much as it does.
From too high up, it’s not going to end well, in other words.
I’m not exactly a science guy, but what matters is the speed you’re moving, in this case, falling, and the fact that water has resistance, sure it’s way less than concrete, but way more than air, otherwise swimming wouldn’t be a thing, we’d just walk through water without being slowed.
One practical example i have in mind, next time you go at sea or a pool, raise your hand up high and slap the shit out of the surface. As hard and as fast as you can. You will see that your hand will be drastically (and maybe painfully) slowed when hitting the water.
Water is sticky to itself. When you go in slow it moves around. Now if you slap a pool of water you feel it. Slaping harder and harder it will fight back more and more. The faster you hit water, the faster it will hit back. It doesn’t have time to move around you and pull itself apart. Fast enough and it will forget it’s a liquid for a brief moment.
This is is called surface tension
and can actually be removed from areas of water. Two example I know of are
I believe where divers land have little jets of water “breaking” the surface tension
This is increased by the stillness of the body of water.
It can be reduced with messing with the stillness
1. With sufficient bubbles you can make non buoyant water with no hope of getting out cause you can’t push off the water like normal and you sink like a rock.
2. Certain areas near the ocean where there is like a rock bowl formation. It is nice and a small pool of water connecting to the ocean in low tide. But when the tide comes it is a raging moshpit of waves causing seafoam to accumulate causing a similar situation to 1 with not buoyant turbulent flow up top and waves crashing into rocks.
Latest Answers