Re: [Phys-l] velocity-dependent mass (or not)

["Craft, Peter" <PETER.CRAFT@det.nsw.edu.au>]

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On 06/23/2009 11:03 AM, David Craig wrote:

> > I'm astonished anyone is still talking about this, let alone teaching
> > it.   (Having seen how egregious are the treatments of relativity in
> > many of the standard "modern physics" textbooks, I do in fact know
> > better than to be surprised.   But I am anyway.)
> >
> > I can't recall meeting ANY professional relativist who employs the
> > concept of a velocity-dependent mass, with the very occasional
> > exception of mention as a throwaway heuristic.  (I have seen one or
> > two of the very old guard use it in public talks, though.)
> >
> > The bottom line is that the concept IS dead among those who actually
> > do relativity for a living.
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John Denker Replied:

> Quite so.
>
> Dead for many, many decades.
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Just as an interesting illustration I thought I would quote from the Physic syllabus document (revised 2003) that I am required (by law) to teach from:

"**explain qualitatively and quantitatively the consequence of special relativity in relation to:
     *the relativity of simultaneity
     *the equivalence between mass and energy
     *length contraction
     *time dilation
     *mass dilation

**discuss the implications of mass increase, time dilation and length contraction for space travel

**Solve problems using
     * l = l(rest) x sqrt (1 - (v^2/c^2))
     * m= m(rest)/sqrt("1- (v^2)/c^2))"
etc

This has kinda forced local textbook writers to discuss velocity dependent mass, which they quite happily do.

Regards

Peter Craft
Head Teacher Science
Corowa High School 
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