So the question was inspired by one of curious comments on youtube. What exactly would happen if you pushed a strong neodymium magnet towards the copper tube (aiming for the opening in an effort to pass it through the tube) while in space?

I'm particularly interested in these 2 cases:
1. The tube is not attached to anything and is freely floating in space.
2. The tube is attached to a relatively massive object (E.g. a shuttle, ISS, etc.), but also assuming that this object does not interact with the magnet or the tube electromagnetically.

I'm unsure if it would manage to pass through while also losing a lot of it's speed gained from the push, or if the forces caused by opposing magnetic field from the current induced in the tube would be able to push against enough so that the two never come close enough, or if it would stop inside the tube, etc.

Thank you.

  • $\begingroup$ Surely this depends on the strength of the magnet, the size of the tube, the initial velocity, the relative masses. There's not enough information here to facilitate an answer. $\endgroup$ – Feyre May 21 '16 at 18:58
  • $\begingroup$ Certainly, for some practical geometries (e.g., copper pipe from the D.I.Y. store, and a strong button magnet) the system will be over-damped, which means that the velocity of the magnet will approach zero during the time that it spends inside the tube. If the tube is long enough (probably not very long) then the magnet will never emerge from the other end. $\endgroup$ – Solomon Slow Oct 16 '19 at 16:19

Faraday's Law of Electromagnetic Induction predicts that the relative motion of the magnet and the copper tube will result in the presence of eddy currents in the tube; . The force relationship is described by Lenz' Law.

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That is, the induced fields oppose the fields that created them. If this were not so, it would be easy to build perpetual motion machines; instead it is impossible.


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