Why doesn't a spinning coin flip over?

[hihiip201]

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

 

[Drakkith]

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".

 

[ehild]

Remember conservation of angular momentum.

ehild

 

[hihiip201]

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.

 

[Drakkith]

oh sorry I should be more clear.

I meant why doesn't it fall down on the ground(flat) as a stationary coin would.

I assume it's similar to why a spinning top doesn't fall over. Conservation of angular momentum and all that.

http://en.wikipedia.org/wiki/Top
http://en.wikipedia.org/wiki/Gyroscope
http://hyperphysics.phy-astr.gsu.edu/hbase/gyr.html#gyr

 

[Meir Achuz]

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.