I thought I would point out a few of the cool, but maybe unnoticed, phenomena that occur in this video. Here goes! ...1/n https://twitter.com/hdanchiano/status/1303798487830728705

1. It is lucky that a big piece of ripped ballon stays in view of the camera. As its rips free, it contracts into a tiny patch, pulling itself across the surface of the water. As it does so, it pulls water with it! That water crashes together and ejects the patch off the surface!

3/ In the prior tweet, tap the images to expand. Or, here they are together.

4/ Another cool thing that happens is the haze that appears all around the balloon right when the red rubber fails and the pulls itself across the water into tiny patches. What is the cause of this haze?

5/ I have a guess. I think that as the rubber rapidly pulled across the water, the friction on the water created a thin layer of water that was also pulled rapidly across the surface. When you have high speed flow, you get turbulence.

6/ Next cool thing. Look at where the pointy stick pierces the balloon. The ballon instantly pulls away, so now the stick is splashing into pure water. What does the water do? It makes a beautiful crown-shaped splash! So gorgeous! For comparison...

7/ Look at a splash from a droplet of red dye landing in a thin layer of milk. It is a gorgeous crown shape! https://www.aps.org/about/physics-images/archive/redsplash.cfm

8/ Same thing coming off the water that was formerly inside a balloon, except the crown is upside down and tilted since the stick hit the surface of the water at an oblique angle.

9/ Here’s an artist’s idea of a giant crown-shaped splash we don’t want to see. At these energy levels, even rock can flow.

10/ The amount of “splash” that occurs is important for deflecting asteroids. Say an asteroid is approaching Earth, so we crash a spacecraft into the asteroid to slightly nudge it off course. The momentum of the spacecraft isn’t the only nudge. The asteroid material splashes...

13/ ...and that splash also pushes the asteroid further in the direction that the spacecraft had pushed it. That is called the “momentum enhancement factor”, and NASA’s DART mission is going to crash into an asteroid’s moon to measure it in 2021. https://directory.eoportal.org/web/eoportal/satellite-missions/d/dart-asteroid

14/ Next cool thing. Notice how the stick exiting the sphere of water pulls a jet of water with it. There would be low pressure behind the stick, so water rushes in the fill the vacuum and gets pulled along behind the stick. But it is a thin jet so it fragments into droplets.

15/ Also not the water jet is pointing a different angle than the stick is pointing. That is because the stick is rotating (pitching down) as it passes through the balloon. The stick’s tail drags the water out at an angle. Same for jumping dolphins.

16/ So why is the stick rotating? Two hypotheses. But first, let’s note that it is NOT rotating before it hits the balloon. Then it IS pitching down while it is in the balloon. Then it STOPS pitching down after exiting the balloon.

17/ Well after looking at it a bunch more times I don’t know so I’m just gonna say I think the tip entering at an angle deflects it, starting the rotation, and the tail dragging water as it comes out slows the stick down again. Not a deeply satisfying explanation

18/ The next fascinating thing is how the jets of water are curved. Why would they curve??? They don’t have lots of tensile strength like a rope, so you can’t whip them and make them curve like a rope. So *how* do they curve??

19/ I believe the answer is that every piece of the jet is not curving, but is traveling in a fairly straight line. (Yeah, there is a tiny *downward* curve due to the pull of gravity, but the upward curve is an illusion).

20/ There’s ANOTHER entire video in this thread with DIFFERENT super-amazing phenomena you can break down. Bonus in this video: it makes a Darth Vader helmet. https://twitter.com/angeleleuve/status/1303933238453448704