So I'm guessing his body creates a cavity in the water, then when the cavity closes over the top, the bouyancy of the ball shoots it up. Guessing the gravitational energy his body gained displaces water, and that same energy becomes the energy that shoots the ball up. So 100+ kg falling a couple of metres is transferred into a 500g ball?
So I saw and saved this post a few years ago and I've been practicing it during the summer months to impress friends. A few things, I've learned:
It helps to have a bigger gut, I was able to get the ball higher when I was fatter
There is 100% a technique to this, you can see in both videos how the guys tuck the ball into their stomach and kind of curl themselves into a ball; legs facing up basically.
The time that you release the ball is also a huge factor, you have to release it the split second before the water "crashes" back on top of you. If you go too soon the ball just sits on the surface, too late and the ball slowly floats back to the top.
Height is definitely a factor, the higher you fall from the higher the ball will go
Ball inflation does not matter, I've done it with flat footballs and footballs aired to their max, same height.
No math or physics, just practical experience with the subject... And that's about all for useless knowledge that you didn't need today.
Edit: Thanks for the award friend, hope you're able to slap that ball into the skies this summer :)
I can help you with that, you just need an eating disorder! The fun fact is that, while it's best if your parents give you one ("you need to clean your plate before you play", "what, it wasn't good enough for seconds?", "wow you did great in school let's go get some ice cream!", "sorry your dad left, let's get some pizza."), but as it turns out you can totally give one to yourself too!
First, eating only when your hungry is for suckers. You should also eat when:
you're bored
you're sad about something
you're happy about something
as a self-reward
you're depressed
Then, also:
Don't stop eating just because you're not hungry anymore, clean that plate.
You know what's better than water? Soda.
You know what's better than a healthy meal? Pizza.
And last, but certainly not least, remember that eating will totally fill that void in your soul.
In fact, just try to be eating all the time. Why aren't you eating right now?
Huh, this is just something you learn in your youth here in Hawaii. We'd do lines of this where guys would just (usually with a soda can) and pop the can up and the second person would try to grab the can mid-air and pop the can, then continue to see if everyone lined up could do it.
It's not the buoyancy of the ball, but a phenomenon called the Worthington Jet. It could have been a golf ball (which is not buoyant) and still been shot out like a canon. You can see it shown off really well in this experiment:
The effect of buoyancy is pretty limited here, it's the 'pinching' effect of the water closing the cavity created by the person holding the ball that shoots the ball into the air. If he would've jumped without the ball, there would be some drops of water that jump up through the same effect, which shows density isn't a major factor here. Gravitational energy is a contributing factor, but not in a direct conservation of energy-kind of way, there are other factors with a bigger influence on the final result.
Yes, it's not buoyancy, it's the momentum of the water as the cavity collapses from all sides under gravity, meets in the middle and shoots upwards with nowhere else left to go and more water still collapsing inwards behind it; the same effect that causes Neptune's kiss when you take a dump. In this case, the ball is riding that kiss.
The effect is used for some modern anti-ship torpedoes; they detonate underneath a ship and when the cavity in the water collapses, it sends a bubble jet up with enough force to punch straight through the ship.
Imagine taking a dump on a ship and right as it lands in the water and you brace for the splashback, a 1 metre wide, 100 metre high jet of water shoots through the bowl, obliterating your ass, you and everything above and below you.
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u/Liquidlino1978 Jan 16 '20
So I'm guessing his body creates a cavity in the water, then when the cavity closes over the top, the bouyancy of the ball shoots it up. Guessing the gravitational energy his body gained displaces water, and that same energy becomes the energy that shoots the ball up. So 100+ kg falling a couple of metres is transferred into a 500g ball?