View Full Version : OT: single direction spinning wooden top

11-05-2012, 08:41 PM
It will spin in one direction regardless of the way you start it:


Paul Alciatore
11-05-2012, 11:46 PM
That is neat. I would love to see an analysis of the physics involved.

11-06-2012, 02:20 AM
The guy said the curvature on the bottom is not centered. That will mean that in one direction, the tendency to lean inwards is balanced by an outward force, and the toy will rotate like a top. In the other direction the toy will roll outwards too easily and the pivot point will change location. In turn that will mean that the thing will change it's center of rotation and give it a roll motion. That motion is like that of a spinning coin running down. The difference is that a coin has a fixed rim on which it contacts the table surface, so it pretty much stays in place. The toy has a much more complex dynamic- the inertia of it rocking translates into spinning, but only in one direction. If you spin it one way, the tendency to rock is diminished and it just spins, but if you spin it the other way, the tendency to rock is increased. But then the rocking motion translates into spinning-

11-06-2012, 02:31 AM
Makes my head hurt!!



11-06-2012, 07:30 AM
Put a slight "S" in the keel. I've done it. It works.