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Physics, Astronomy & Cosmology / Re: Does a particle's weight increase with speed? More on relativistic mass.
« on: 23/07/2016 11:29:49 »I came across a special relativity text which says A particle does not become heavier with increasing speed. Do you believe the author is correct?I think it's wrong, on the particle there should be a greater force, proportional to the gamma factor. But maybe the author intended to refer to its mass and not to its weight (which kind of book is it? Is it a universitary text?)
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What would you expect would happen to the magnitude of the gravitational field if the source of the field was moving?Don't know, but is it really the same question as the particle's weight?
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Authors who don't use and don't like the concept of relativistic mass make arguments such as the following which are from Appendix F in the text Special Relativity by T.M. Helliwell page 259. I'm going to paraphrase a bit to save myself some typing but the essence of what I'm quoting will not be changed. The author uses the symbol mR to represent relativistic mass.I agree with these three points and I would even add others, but I've already discussed about them in many other threads. All of this in SR only, however, even because I don't know anything of GR.Quote(i) By hiding √{1 - v2} in the mass, we may forget it is there. ...
(ii) One may get the mistaken impression that to go from classical to relativistic mechanics its only necessary to replay all masses by mR. This certainly works for the momentum p = mRv, but it does not work, for example, for kinetic energy: The relativistic kinetic energy is not (1/2)mRv2. And it works in Newton's second law F = ma only in the very special case where the force exerted on a particle is perpendicular to its velocity. In all other cases F != ma.
(iii) Relativity fundamentally serves to correct our notions about time and space. That is, it is really the dynamical equations dealing with motion, like energy and momentum, that ought to be changed, and not the properties of individual particles, like mass.
(iii) When relativity is cast in four-dimensional spacetime form, ...., the idea of relativistic mass is out of place and clumsy.
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