Explaining The Spinning Water Demo

In this video I go into the physics of my spinning water demo. I derive the exact curve of the water surface using simple high school physics and math.

It turns out that the shape is a parabola! more specifically it's a paraboloid, but my thin tank only shows a cross section of it.

I use the derived curve to estimate how fast the tank spins. I was able to verify the obtained value by directly measuring the RPM, and it seems that everything holds up :)

If you wish to build this yourself, check out the build post.