The Euler Disc Is The Wrong Shape

Summary by Krater

The creator investigates the physics of spinning discs on mirrored bases, testing various shapes, mass distributions, roundness, base stiffness, and curvature to determine what maximizes spin time.

From the video

Answers: Why do some spinning discs spin longer than others and how can you optimize their design?

• Spinning disc physics
• Euler's disk
• Contour friction
• Rolling friction
• Mass distribution
• Edge roundness
• Base stiffness
• Base curvature

What it concludes

• Contour friction, caused by deformation at the rolling contact point, is the main culprit robbing spinning discs of their energy rather than air resistance.
• A ring shape does not spin longer than a solid disc despite having more kinetic energy near the edge, because mass distribution changes don't overcome contour friction limits.
• A cone shape (frustum) performs about as well as a disc at larger scales, but extra mass dissipation and wobble make cone shapes less beneficial.
• An edge roundness of approximately 1 mm radius provides the best performance by reducing deformation and contour friction.
• Tungsten discs spin longer than steel or titanium cones because the extra initial kinetic energy from tungsten's high density outweighs mass distribution changes.