Why isn't there any friction in magnet trains?

[DiMer]

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

 

[A.T.]

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

It has low friction.
http://en.wikipedia.org/wiki/Magnetic_bearing#Applications

 

[mfb]

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.

 

[Rebekah Barker]

Considering we cannot make an absolute vacuum on Earth, there would still be some air resistance as well.

 

[mfb]

We can make a vacuum so good a train could circle the Earth for millions of years without needing acceleration if there wouldn't be any other losses. That is not a guess, it is the result of a calculation.

 

[rootone]

Wouldn't be very good as a passenger service though

 

[mfb]

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.