Re: Mass/Energy concepts and terminology

[Jim Green <JMGreen@SISNA.COM>]

I agree with Leigh and John here:  Leigh I used "weight" because the term
"mass" was getting too sticky in this thread -- not to be cute.  My
original comment was meant to say that it is a bit provincial to say that
"mass" is "converted" to "energy" or the like.   In the present case and
all others I can think of at the moment, if the energy of a system is
increased, its mass is increased also.  Now this may unnerve those who want
to disparage the term "rest mass"  and despise the use of other than rest
mass and total energy of a system in E=mc^2, but there you are.  BTW I do
not mind at all saying that a photon (what ever that may be) exhibits
relativistic mass.   But I am old and senile

Jim

At 17:45 11 12 2000 , you wrote:
> An iceberg and a system consisting of the water equivalent of the
> iceberg (the same number of molecules) have different masses, the
> melted phase being the more massive of the two by an amount given
> the internal energy difference divided by the speed of light squared.
>
> Are you being cagey by using "weight", Jim? That just complicates
> the question. The important conceptual point is the mass difference.
> In the same uniform gravitational field (or equivalent thereof) the
> water will evidently weigh more than the iceberg.
>
> Leigh


Jim Green
mailto:JMGreen@sisna.com
http://users.sisna.com/jmgreen