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Re: are normal reaction and tension conservative ?

At 01:47 PM 6/30/01 -0400, Chuck Britton wrote:

Back in the late '60's, some dude named Goldstein had a text book on
Classical Mechanics


that left me with the IMPRESSION that any
velocity dependent force is non-conservative.

Almost any. A charge moving slowly through a constant magnetic field is
the obvious exception, because the force is normal to the velocity, as
Chuck noted:

When presenting magnetic forces (QvB) to neophytes we say that no
work is done since the force is normal to the displacement.


(When DOES the radiative component enter into our curriculum?)

Maybe when the charge moves more quickly?

I can also say the words 'holonomic(sp),

That constrains the system to a subspace of whatever state space it would
otherwise have had:


That's usually "scleronomic". Same as above, with the added feature that
the constraint equation has no explicit time-dependence.

As a rough analogy: in chess, the bishop is subject to a scleronomic
constraint (always red or always black); the knight's constraint is
non-scleronomic (alternating red and black) if we interpret "time" to be
the number of moves that piece has made.