spinning tops experiment

[Diamabolo]

...after seeing this on insta @physicsfun, I had to rebuild this physic toy
still have no idea what is causing this phenomenon

[pleegwat]

I suspect it's friction causing a transfer of angular momentum.

[Frequenzberater]

I think its a matter of friction with the surrounding air. 

I am confident this wont work in a vacuum. 

[Diamabolo]

thanks for your feedback..
I have now also tested a motorized version ... and with it the carousel does not start moving!
so the friction seems to be responsible
I will probably not be able to test the whole thing under vacuum

[Axadder]

18 hours ago, Frequenzberater said:

I think its a matter of friction with the surrounding air. 

I am confident this wont work in a vacuum. 

I suppose it so.

Try with different tire configurations and see the times it takes to accelerate.

[Toastie]

I also believe so. Air is a viscous medium, so you constantly "couple" the rotating wheel surface with that medium, resulting in the motion of the "rotor".

It will become even clearer when you attach little paddle type things to the wheels. In essence this is what propels a boat forward when using a propeller ;). Water has of course a much higher viscosity than air and the wheels you are using are really badly designed propellers , but ...  

5 hours ago, Diamabolo said:

and with it the carousel does not start moving!

Do both wheels spin in the same direction in setup #2? Other than that (except much stronger friction at the ball-type bearing due to increased weight of the rotor) I don't see why it would not start to spin ...

What happens, when you have the wheels in setup #1 don't spin in the same direction?

You can also use a hair dryer and see what a additional wind direction at one side of the wheels would cause. Fun experiments!

Best
Thorsten

[Diamabolo]

On 1/12/2022 at 5:22 PM, Toastie said:

Do both wheels spin in the same direction in setup #2?

...yes they do.
Thanks for the feedback. Good ideas to experiment with