🚀 go-pugleaf

In article <mcirvin.712113680@husc8> mcirvin@husc8.harvard.edu (Mcirvin) writes:

> >	It's perfectly reasonable to talk about the mass of a
> >	macroscopic object.  The inertial mass of the object
> >	can be operationally defined in terms of the force
> >	that has to be applied to the object to produce a given
> >	rate of acceleration. 
> 
> In order to spare straw personnel further injury, let me state that
> the relativistic mass is obtained in this manner not from F = ma,
> but from F = dp/dt and p = mv.

I'm not at all sure that this is just a straw man: I believe that one
of the dangers of "relativistic mass" is that it leads people to
believe (mistakenly) that, using this as the "m" in equations of
Newtonian kinematics, these equations still remain valid
relativistically.

I think it is worth pointint out that many Newtonian equations have to
be modified in a relativistic context, and that, no matter what
definition of mass is used, equations like F=ma and E=(1/2)mv^2 are
only valid in the nonrelativistic regime.

Certainly the original poster suggested that he wanted to define mass
to be the constant of proportionality between force and acceleration,
not that he wanted it to be the constant of proportionality between
velocity and momentum.
--
Matthew Austern              I dreamt I was being followed by a roving band of
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matt@physics.berkeley.edu    taunting me and shouting, "Politically correct
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