Discover the Fascinating Physics of the Tippe Top | Princeton Physics Dept.

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Discussion Overview

The discussion centers around the physics of the Tippe Top, particularly its behavior when spun and the mechanisms behind its flipping motion. Participants explore concepts related to torque, friction, and the dynamics of spinning objects, including comparisons to other shapes like spheres and M&Ms. The conversation includes references to academic articles and videos demonstrating the phenomena.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants propose that the flipping of the Tippe Top is due to contact torque.
  • Others mention that the flipping behavior is unrelated to the "polhode rolling on the herpolhode" instability discussed in classical mechanics literature.
  • A participant questions whether an M&M spinning on a frictionless surface would behave like a sphere, suggesting it might not right itself.
  • Another participant clarifies that for a sphere, the force is always directly below the center of gravity, while for an M&M, this is only true in specific orientations, leading to torque even on a frictionless surface.
  • A later reply introduces a paper that attributes the flipping of the Tippe Top to frictional losses, arguing that without friction, inversion cannot occur.
  • One participant speculates that angular momentum and friction might convert kinetic energy into raising the center of gravity.

Areas of Agreement / Disagreement

Participants express differing views on the role of friction and torque in the behavior of the Tippe Top and similar objects. There is no consensus on the mechanisms involved, with multiple competing explanations presented.

Contextual Notes

Some claims depend on specific definitions of torque and friction, and the discussion includes unresolved assumptions about the conditions under which the Tippe Top operates.

Bob S
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Here is an article via the Princeton Physics Dept. on the Tippe Top (Tipsey Turvy Top) that will flip upside down when you spin it. The flipping is apparently due to contact torque.

http://www.google.com/url?sa=t&source=web&cd=2&sqi=2&ved=0CBkQFjAB&url=http%3A%2F%2Fwww.physics.princeton.edu%2F~mcdonald%2Fexamples%2Fmechanics%2Fpliskin_ajp_22_28_54.pdf&ei=7ge9TL3mG8bMswarkqTJDQ&usg=AFQjCNEyFqkkE6PtYF8gf_5fD-MhV0xwzQ&sig2=IYVOWaouG1Wrej123gMX0w

This is unrelated to the "polhode rolling on the herpolhode in the invariable plane" instability discussed in Goldstein "Classical Mechanics", which can be easily demonstrated with a book (held shut with a rubber band).

Bob S
 
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Bob S said:
Here is an article via the Princeton Physics Dept. on the Tippe Top (Tipsey Turvy Top) that will flip upside down when you spin it. The flipping is apparently due to contact torque.

http://www.google.com/url?sa=t&source=web&cd=2&sqi=2&ved=0CBkQFjAB&url=http%3A%2F%2Fwww.physics.princeton.edu%2F~mcdonald%2Fexamples%2Fmechanics%2Fpliskin_ajp_22_28_54.pdf&ei=7ge9TL3mG8bMswarkqTJDQ&usg=AFQjCNEyFqkkE6PtYF8gf_5fD-MhV0xwzQ&sig2=IYVOWaouG1Wrej123gMX0w

This is unrelated to the "polhode rolling on the herpolhode in the invariable plane" instability discussed in Goldstein "Classical Mechanics", which can be easily demonstrated with a book (held shut with a rubber band).

Bob S

So if the M&M was spinning on a perfectly frictionless surface in a vacuum would it just spin like a sphere does with friction?
 
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FREEDOM2 said:
So if the M&M was spinning on a perfectly frictionless surface in a vacuum would it just spin like a sphere does with friction?

I don't know if I follow, but you're right in that there would be no reason for it to right itself.
 


FREEDOM2 said:
So if the M&M was spinning on a perfectly frictionless surface in a vacuum would it just spin like a sphere does with friction?
Actually not. For a sphere, the point of contact, and the point of vertical force mg, is always directly below the center of gravity (CG). For an M&M, the force is directly below the CG only for two special orientations. When this force is not directly below the CG, there is a torque on the M&M, even if the contact is frictionless.

Bob S
 


Bob S said:
Here is an article via the Princeton Physics Dept. on the Tippe Top (Tipsey Turvy Top) that will flip upside down when you spin it. The flipping is apparently due to contact torque.

http://www.google.com/url?sa=t&source=web&cd=2&sqi=2&ved=0CBkQFjAB&url=http%3A%2F%2Fwww.physics.princeton.edu%2F~mcdonald%2Fexamples%2Fmechanics%2Fpliskin_ajp_22_28_54.pdf&ei=7ge9TL3mG8bMswarkqTJDQ&usg=AFQjCNEyFqkkE6PtYF8gf_5fD-MhV0xwzQ&sig2=IYVOWaouG1Wrej123gMX0w
Here is a much more recent (and much longer) paper that also attributes the flipping to frictional losses. Moreover, they show that without frictional losses the inversion cannot occur.

Bou-Rabee et al. (2008), Dissipation-Induced Heteroclinic Orbits in Tippe Tops, SIAM Review, 50:2, 325-344
http://authors.library.caltech.edu/10958/1/BOUsiamr08.pdf
 
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Bob S said:
Actually not. For a sphere, the point of contact, and the point of vertical force mg, is always directly below the center of gravity (CG). For an M&M, the force is directly below the CG only for two special orientations. When this force is not directly below the CG, there is a torque on the M&M, even if the contact is frictionless.

Bob S

Thanks for explaining! I thought that origination of the torque was due to the friction...