- #1
Tazerfish
- 119
- 24
The main question is in the title.
1.I have wondered if a regular pencil would precess and rotate stable for multiple seconds if spun fast enough.
[Coins, plates, bowls and similarly shaped objects can rotate in a stable way for extended periods of time.
And a lot of other household objects can be put into some kind of stable rotation. That is what inspired this question.
Though technically the rotation described above is fundamentally different from a top, since the point of contact constantly changes.
(I wouldn't mind learning something about the kind of motion mentioned above, but the main question is the one from the title)]
Yet there are examples which are basically identical to tops, for instance a cube(dice).
2.Could rectangles which aren't cubes spin on their corners ?
If the answer to the main question is no, only specific objects can rotate in a stable fashion on a flat surface for long periods of time, then 3. I would like to know the criteria necessary for a suitable shape.
Does it have to be symetrical I am some sense?
Does it have to have a certain minimum ratio of moment of inertias between its "falling over axis" and "spinning axis" ?
4.I would also be interested how to calculate the minimum angular velocity necessary to produce stable precession (dependant on some parameters).(for example for a pencil)
Sorry that there are so many different questions.Feel free to just answer one of them.
1.I have wondered if a regular pencil would precess and rotate stable for multiple seconds if spun fast enough.
[Coins, plates, bowls and similarly shaped objects can rotate in a stable way for extended periods of time.
And a lot of other household objects can be put into some kind of stable rotation. That is what inspired this question.
Though technically the rotation described above is fundamentally different from a top, since the point of contact constantly changes.
(I wouldn't mind learning something about the kind of motion mentioned above, but the main question is the one from the title)]
Yet there are examples which are basically identical to tops, for instance a cube(dice).
2.Could rectangles which aren't cubes spin on their corners ?
If the answer to the main question is no, only specific objects can rotate in a stable fashion on a flat surface for long periods of time, then 3. I would like to know the criteria necessary for a suitable shape.
Does it have to be symetrical I am some sense?
Does it have to have a certain minimum ratio of moment of inertias between its "falling over axis" and "spinning axis" ?
4.I would also be interested how to calculate the minimum angular velocity necessary to produce stable precession (dependant on some parameters).(for example for a pencil)
Sorry that there are so many different questions.Feel free to just answer one of them.