Question from johnreed for PD
in [Relativity]
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From: Uncle Ben on 25 Jul 2010 17:51 On Jul 25, 3:21 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Uncle Ben" <b...(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? Dear John, If we follow your reasoning about the smallest real number greater than zero, we find that it is your IQ. Napoleon Bomehead
From: Androcles on 25 Jul 2010 18:24 "Uncle Ben" <ben(a)greenba.com> wrote in message news:32d9e380-abbc-43a3-9f51-f0f26ece423c(a)z10g2000yqb.googlegroups.com... On Jul 25, 3:21 pm, "Androcles" <Headmas...(a)Hogwarts.physics_z> wrote: > "Uncle Ben" <b...(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? Dear John, If we follow your reasoning about the smallest real number greater than zero, we find that it is your IQ. Napoleon Bomehead ========================================== 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 zero when the force is zero, to match your IQ, right, Napoleon? At least you recognise my IQ is greater than zero.
From: thejohnlreed on 26 Jul 2010 05:07 Daryl McCullough View profile More options Jul 25, 5:50 am thejohnlreed says... - Show quoted text - 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 jr writes> Thanks for the response Daryl. That's not the question I seek an answer to. I want a precise word definition for mass that doesn't reduce to an amount of matter. I say that mass is not an amount of matter. Mass is the quantitative measure of the conserved (cumulative) resistance of an amount of matter. This conserved cumulative resistance is the sum of the resistance of the atoms that make up an object that we act on. This definition does not apply to particles nor does it apply to photons. It does not apply to the celestial universe. The fact that we continue to use mass beyond the frame where it is conserved shows that we in fact do think that mass is an amount of matter rather than a conserved (cumulative) resistance of an amount of matter. Which is the conserved cumulative resistance of a number of atoms. Thanks again. jr
From: harald on 26 Jul 2010 05:33 On Jul 26, 11:07 am, thejohnlreed <thejohnlr...(a)gmail.com> wrote: > Daryl McCullough > View profile > More options Jul 25, 5:50 am > thejohnlreed says... > > - Show quoted text - > 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 > > jr writes> > Thanks for the response Daryl. That's not the question I seek an > answer to. I want a precise word definition for mass that doesn't > reduce to an amount of matter. I say that mass is not an amount of > matter. Mass is the quantitative measure of the conserved (cumulative) > resistance of an amount of matter. This conserved cumulative > resistance is the sum of the resistance of the atoms that make up an > object that we act on. This definition does not apply to particles nor > does it apply to photons. It does not apply to the celestial universe. > The fact that we continue to use mass beyond the frame where it is > conserved shows that we in fact do think that mass is an amount of > matter rather than a conserved (cumulative) resistance of an amount of > matter. Which is the conserved cumulative resistance of a number of > atoms. Thanks again. jr You could try the view that mass is a measure of energy content, or E/ c^2. That even works for photons, see: http://www.xs4all.nl/~johanw/PhysFAQ/ParticleAndNuclear/photon_mass.html You can literally weigh its mass on a balance, or measure it indirectly by applying the laws of motion or gravitation. Harald
From: thejohnlreed on 26 Jul 2010 05:57
Uncle Ben View profile More options Jul 25, 11:30 am 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. jr writes> Interesting. 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) } jr writes> Unfortunately the mass of an object has always been defined on the basis of the definition of force. I asked for a word definition that did not reduce to an amount of matter. You provide a mathematical definition in terms of force.. Which reduces to an amount of matter that we measure and feel, or weight F=mg. There are other equivalent definitions. The expression within the braces {} is defined as the momentum of the particle. jr writes> See my response to Daryl. Mass is not conserved wrt particles. So we switchtomomentum and energy. That you wish to define particles in terms of mass shows that it is an amount of matter to you. It is the conserved cumulative resistance of an object composed of atoms. The cumulative resistance of those atoms. 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. jr writes> My case in point. No longer conserved but an invariant amount of matter. Thanks for the reply. These answers are appreciated. Have a good time. jr |