# Animation of the 'rising-egg' phenomenon.

When a hard-boiled egg is spun sufficiently rapidly on a table with its axis of symmetry horizontal,
the axis will rise from the horizontal to the vertical. The egg’s center of mass rising against gravity.
The equations of motion from [1] were simulated to make this animation.

[1] Moffatt, H. K., Shimomura, Y. & Branicki, M., 2004, ”Dynamics of an axisymmetric
body spinning on a horizontal surface. I. Stability and the gyroscopic
approximation”, Proc. R. Soc. A. 460, 3643-3672.

jellybean:spin:

Interesting, have you tried it with a real egg? How did you do it in blender?

I havent heard of this rising egg thing before. So if I spin an egg it should do this? ( or it’ll just fall of the kitchen table and smash lol)
What did you use to turn the maths into motion?

It must be a hard boiled egg. A raw egg will not work because of the fluid inside. Give it a good fast spin and it will “rise”.
I wrote a python script to calculate the eulerian angles phi, theta, psi and location of the spheroid cg verses time. The script then generates location rotation keyframes for the spheroid object. Unfortunately blender’s euler angles are not the same as the classical eulerian angles so I had to first calculate a direction cosine matrix from the eulerian angles and then use Matrix.to_euler() to get the euler angles blender uses.

Neeeeerddd! Lol, that is pure envy. Python is one of those things that is as hard to learn as blender itself, kudos to you sir!
I’ll have to try the thing with the egg, I thought that a raw egg would work because of the dynamic inertia and density difference of yolk vs white.

OK. Real nice one.