Physics Stack Exchange is a question and answer site for active researchers, academics and students of physics. It's 100% free.

Sign up
Here's how it works:
  1. Anybody can ask a question
  2. Anybody can answer
  3. The best answers are voted up and rise to the top

If you were to build an upright machine that had a rod fitted into a ball bearing at the base and was secured to another rod at the top of the initial rod extending perpendicularly. To which you attached a magnet, and around this machine you also placed several upright rods containing magnets that would push/pull the magnet attached to the rod, would this cause the initial magnet to spin the machine for some period of time?

(Assuming I'm giving the machine a push to start the motion initially)

Inevitably, provided the above would work, friction would lead to an eventual slowing. With that said is there anyway to postpone that slowing for a reasonable period of time? Can magnetic shielding be used in any fashion to maintain the motion for longer?

share|cite|improve this question
are you giving it an initial push to get going? – Jim Apr 26 '13 at 22:15
Yes I suppose it won't work otherwise, not without some kind of motor or battery anyway. – DeeplyConfused Apr 26 '13 at 22:21
In that case, I think what you're describing is essentially a magnetic bearing. – Jim Apr 26 '13 at 22:28
So this will work then? Certainly not indefinitely, but for a period of time without me having to play with it? Ideally this machine is spinning for a reasonable amount of time- is that too possible? – DeeplyConfused Apr 26 '13 at 22:31
I think the magnets may need to be powered and alternating in direction, otherwise they would increase resistance rather than decrease it. But I could be wrong; I'm sure the internetz could elaborate more about mag bearings – Jim Apr 26 '13 at 22:37

Your Answer


By posting your answer, you agree to the privacy policy and terms of service.

Browse other questions tagged or ask your own question.