I Air friction in rotating ring magnet

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The discussion focuses on calculating air friction for a rotating middle ring magnet positioned between two others. Participants inquire about the polarization of the magnets, the stabilization method for the middle magnet, and the generation of rotational force. Suggestions include using a vacuum chamber to eliminate air friction, allowing for theoretical perpetual rotation. The conversation also touches on the importance of understanding the research already conducted on air resistance. Overall, the thread seeks to clarify the mechanics and applications of the rotating magnet system.
Jaap
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Air friction in rotating ring magnet
As can be seen below we have 3 ring magnets. The middel one floats in between the other two. We want to know how to calculate the air friction of the middle ring magnet if this rotates.
Schematic ringmagnets.jpeg
 
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Hi. I do not have scarce knowledge of air friction and it seems complicated. Why don't you put your system in a vacuum chamber ? Without friction the intermediate disk would rotate forever theoretically.
 
Welcome to PF. :smile:

Jaap said:
As can be seen below we have 3 ring magnets. The middel one floats in between the other two. We want to know how to calculate the air friction of the middle ring magnet if this rotates.

First some questions -- How are the 3 ring magnets polarized? Vertically or horizontally or some mix? What stabilizes the middle ring magnet between the other 2? How do you generate a rotational force to spin up the middle magnetic ring?

And on your question about air resistance -- what have you found in your research so far?

Finally, is this question for schoolwork? If not for scholwork, what is the application? Thanks.
 
Thread 'Why higher speeds need more power if backward force is the same?'

Thread 'Why higher speeds need more power if backward force is the same?'

Power = Force v Speed Power of my horse = 104kgx9.81m/s^2 x 0.732m/s = 1HP =746W Force/tension in rope stay the same if horse run at 0.73m/s or at 15m/s, so why then horse need to be more powerfull to pull at higher speed even if backward force at him(rope tension) stay the same? I understand that if I increase weight, it is hrader for horse to pull at higher speed because now is backward force increased, but don't understand why is harder to pull at higher speed if weight(backward force)...
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