Flying Circus of Physics: Tea Leaf Effect (Episode 2.6)

[@marielizysurourcq]

First, I would like to thank you for the influence you had on my life. I liked to read all kinds of stuff in the library in the 80s and not only comics. I found your book in French and loved it and bought two copies one day eventually (now lost). I was very average at school but all your questions fascinated me more than the (short) answers. Eventually, I got a fluid mechanics engineer diploma in the mid 90s. Now, I must admit that I think your explanation is wrong (as is Einstein, yeah, he could be wrong sometimes as well...). I'm actually checking that in Wikipedia and found in the talk section a guy who thinks like me (wikipedia is not wrong but very unclear right now). This is a summary : "In short, you stir the spoon and create a centrifugal rotational effect. Now, this centrifugal force creates a PARABOLOID (important word) shape of the surface. This shape makes pressure (simple total height of fluid column) higher on the side than in the center; this entails a pressure gradient on the whole fluid and this pressure gradient tends to compensate the centrifugal force. YET ! There is a boundary layer effect (aka friction) on the bottom that slows down the centrifugal inertia but not the pressure gradient which is the highest there and so leaves which are at the bottom follow this inward pressure gradient and can even rise when the flow which reach the center at the bottom tend to go where it can (up a bit if they are light enough)." I have a source but it's in French www.bibnum.education.fr/sites/default/files/analyse-einstein-tea.pdf

[@dennisbroadway5085]

Always great! Please keep them coming.

[@FlyingCircusofPhysics]

We will! Stay tuned for Season 3 this fall.

[@jimjackson4256]

So what if the walls of the container are all at the same diameter from top to bottom?

[@jonas162]

this was somehow strangely entertaining, btw thank you this has helped me a lot