Why doesn't a spinning coin flip over?

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    Coin flip Spinning
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Discussion Overview

The discussion centers on the question of why a spinning coin does not fall flat on the ground like a stationary coin. Participants explore both qualitative and mathematical explanations related to the physical principles involved, including angular momentum and rotational dynamics.

Discussion Character

  • Exploratory, Technical explanation, Conceptual clarification

Main Points Raised

  • Some participants inquire about the meaning of "flip over" in the context of a spinning coin and clarify that they are asking why it does not fall flat like a stationary coin.
  • One participant mentions the conservation of angular momentum as a key principle that may explain the behavior of the spinning coin.
  • Another participant draws a parallel between the spinning coin and a spinning top, suggesting that similar principles apply to both, particularly conservation of angular momentum.
  • A later reply introduces Euler's equations, discussing the relationship between angular velocities and moments of inertia, indicating that certain conditions lead to oscillation without flipping over.

Areas of Agreement / Disagreement

Participants express varying interpretations of the question and the underlying physics, with no consensus reached on a singular explanation or model for the behavior of the spinning coin.

Contextual Notes

Some assumptions about the physical conditions and definitions of terms like "flip over" remain unresolved, and the discussion does not fully explore the mathematical modeling aspects requested by the initial post.

hihiip201
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As titled:


I would be satisfied with a qualitative explanation(pure physical), but it would be nice if someone can also provide the mathematical model.



thanks
 
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Are you asking why it doesn't stop spinning and flop over onto one of its sides? Just not sure what you mean by "flip over".
 
Remember conservation of angular momentum.

ehild
 
Drakkith said:
Are you asking why it doesn't stop spinning and flop over onto one of its sides? Just not sure what you mean by "flip over".



oh sorry I should be more clear.

I meant why doesn't it fall down on the ground(flat) as a stationary coin would.
 
It follows from Euler's equations. If there is an Omega_z (z is the axis of the coin), and I_z is larger than I_x and I_y, Omega_x and Omega_y follow SHO, and oscillate without flipping over.
You can win money with that, just don't get caught.
 

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