Why isn't there any friction in magnet trains?

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Discussion Overview

The discussion centers around the concept of friction in magnet trains, particularly in a vacuum environment. Participants explore the implications of gravitational forces, electron interactions, and the effects of air resistance on the operation of magnet trains.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant questions whether a magnet train in a vacuum experiences no friction, suggesting that electron interactions due to gravitational forces might play a role.
  • Another participant asserts that while a magnet train in vacuum has low friction, it is not entirely frictionless.
  • It is mentioned that inhomogeneous magnetic fields could introduce some friction through mechanisms like eddy current braking.
  • A participant points out that even in a vacuum, air resistance would still be a factor, as achieving a perfect vacuum on Earth is not feasible.
  • One participant claims that calculations indicate a train could theoretically circle the Earth for millions of years without needing acceleration if all other losses were eliminated.
  • Another participant notes that achieving the best possible vacuum for a train would be prohibitively expensive, but a sufficiently good vacuum could render friction from remaining gas atoms negligible.

Areas of Agreement / Disagreement

Participants express differing views on the nature and extent of friction in magnet trains, with no consensus on whether they can be considered completely frictionless or the implications of gravitational and electron interactions.

Contextual Notes

Limitations include assumptions about the vacuum quality achievable on Earth and the potential effects of various forces and interactions that have not been fully explored or quantified in the discussion.

DiMer
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Hi there, first poster here.

Something has been boggling me and I cannot seem to find the answer anywhere. I really hope that you will help me =)

A magnet train in vacuum has no friction whatsoever, right?

Then what about electron interactions between the 'rail' and the train itself due to the gravitational force?
I understand that if it was in space the train with would be in a perpetual motion and it would never stop. But if it's affected by gravity, why would it not move infinately? Is there some electron interactions between the rail and the train, or is it completely frictionsless?

Maybe I'm asking the wrong question, but if you would help me I'd really appreciate it!

Thank you
 
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DiMer said:
A magnet train in vacuum has no friction whatsoever, right?
It still has some friction from inhomogeneous magnetic fields as they can act like an eddy current brake.

Gravity gives a very homogeneous potential, and no friction involved.
 
Considering we cannot make an absolute vacuum on Earth, there would still be some air resistance as well.
 
Wouldn't be very good as a passenger service though
 
Well...

A vacuum tube for a train would not get the best vacuum we can make, that would be way too expensive. But we can make a vacuum so good that friction with the remaining gas atoms becomes completely negligible.
 

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