Question from johnreed for PD
in [Relativity]
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From: thejohnlreed on 25 Jul 2010 00:58 Or for anyone else that has an answer> jr wrote>> But if I am incorrect there > it has nothing to do with my primary focus. > Its not the measure of mass in various ways that concerns me. It is > the definition of mass that is most important especially because we > require no greater accuracy in that definition than "amount of > matter". PD wrote> And that is wrong, as I've indicated. jr writes> I have reviewed the responses to my original post, seeking what you say you have indicated. I find nothing to support what you claim you have indicated. Saying it is wrong is not sufficient. I do not mind being wrong having been wrong thousands of times in the past. But just saying I am wrong is not enough. Please provide the word definition for mass that amounts to something more than an amount of matter. This is after all, what Newton provided and Einstein built on. I admit it is all I have to reference. Thanks. Have a good time. johnreed
From: Daryl McCullough on 25 Jul 2010 08:50 thejohnlreed says... > >Or for anyone else that has an answer> > >jr wrote>> But if I am incorrect there >> it has nothing to do with my primary focus. >> Its not the measure of mass in various ways that concerns me. It is >> the definition of mass that is most important especially because we >> require no greater accuracy in that definition than "amount of >> matter". > >PD wrote> >And that is wrong, as I've indicated. > >jr writes> >I have reviewed the responses to my original post, seeking what you >say you have indicated. I find nothing to support what you claim you >have indicated. Saying it is wrong is not sufficient. The reason that "amount of matter" is not quite correct as a definition of mass is because the same pieces of matter can have different masses depending on the circumstances. For example, an electron and a proton that are combined into a hydrogen atom will have a smaller mass than an electron and proton when they are apart. Also, a collection of photons can together have a mass, even though no single photon has a nonzero mass. -- Daryl McCullough Ithaca, NY
From: Uncle Ben on 25 Jul 2010 14:30 On Jul 25, 8:50 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > thejohnlreed says... To add to Daryl's connent: The "quantity of matter" definition is given in some high school texts for students who don't yet know enough physics to comprehend a more precise definition. The better definition is that the mass of a particle is defined on the basis of the definition of force, with the result that it is the constant quantity m in F = d/dt { mv/sqrt(1-v*v/c*c) } There are other equivalent definitions. The expression within the braces {} is defined as the momentum of the particle. In earlier times, one defined the "relativitic mass" as rest mass divided by the sqrt expression above. Nowadays we avoid that term so as to consider m an invariant constant.
From: Androcles on 25 Jul 2010 15:21 "Uncle Ben" <ben(a)greenba.com> wrote in message news:9c767987-eab5-4a5e-a8e5-186dd0ade1e9(a)x21g2000yqa.googlegroups.com... On Jul 25, 8:50 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) wrote: > thejohnlreed says... To add to Daryl's connent: The "quantity of matter" definition is given in some high school texts for students who don't yet know enough physics to comprehend a more precise definition. The better definition is that the mass of a particle is defined on the basis of the definition of force, with the result that it is the constant quantity m in F = d/dt { mv/sqrt(1-v*v/c*c) } ======================================== To add to Bomehead's connemt: If v = 0, what is the comstamt quamtity m of natter, Napoleon Bomehead?
From: eric gisse on 25 Jul 2010 17:47
Uncle Ben wrote: > On Jul 25, 8:50 am, stevendaryl3...(a)yahoo.com (Daryl McCullough) > wrote: >> thejohnlreed says... > > To add to Daryl's connent: > > The "quantity of matter" definition is given in some high school texts > for students who don't yet know enough physics to comprehend a more > precise definition. > > The better definition is that the mass of a particle is defined on the > basis of the definition of force, with the result that it is the > constant quantity m in > > F = d/dt { mv/sqrt(1-v*v/c*c) } > > There are other equivalent definitions. The expression within the > braces {} is defined as the momentum of the particle. Or, better yet, the T_00 component of the stress-energy tensor. > > In earlier times, one defined the "relativitic mass" as rest mass > divided by the sqrt expression above. Nowadays we avoid that term so > as to consider m an invariant constant. |