The Size of Avogadro's number
in [Physics]
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From: jbriggs444 on 18 May 2010 14:57 On May 18, 1:06 pm, david.bostw...(a)chemistry.gatech.edu (David Bostwick) wrote: > In article <0777d4e9-d5a3-4dd4-b88f-f00e66256...(a)v12g2000prb.googlegroups..com>, jbriggs444 <jbriggs...(a)gmail.com> wrote: > > [...] > > > > >Contrary to what physics jargon might suggest, the act of "weighing" > >an object > >normally means "determine the mass of the object". [My chemistry > >teacher > >objected to this disharmony and insisted that we use "mass" as a verb > >to describe > >the operation. 'Let us put the object on a scale and mass it'] > > Mass does not change. Weight does, because weight is affected by the > gravitational force on the mass. That's why the formula for inertia doesn't > contain g, but only m and v. I'll "mass" the same on the Earth or the Moon, > or in a space station, and I'll have the same inertia, but I definitely won't > weigh the same. > > [...] But if you weigh yourself, you will get the same result. Assuming that you use a properly calibrated scale.
From: jbriggs444 on 18 May 2010 15:01 On May 18, 1:44 pm, glen herrmannsfeldt <g...(a)ugcs.caltech.edu> wrote: > In sci.physics jbriggs444 <jbriggs...(a)gmail.com> wrote: > (big snip) > > > Contrary to what physics jargon might suggest, the act of "weighing" > > an object normally means "determine the mass of the object". > > [My chemistry teacher objected to this disharmony and insisted > > that we use "mass" as a verb to describe the operation. > > 'Let us put the object on a scale and mass it'] > > It really does not matter whether you use a spring or a balance. > > You are measuring the same quantity. > > I disagree, but it does depend on how you do it... > > > > > In the case of a balance, you are comparing the unknown mass in the > > test pan against a [set of] known mass[es] in the reference pan. > (snip) > > You are doing this based on an assumption that the arms are equal > > and that the difference in the acceleration of gravity at the > > one pan is [nearly] identical to the acceleration of gravity at the > > other. > > (snip) > > > In the case of a spring scale or load cell, you are comparing the > > unknown mass in the test pan against the set of known masses > > that the scale was calibrated against. > > If you recalibrate often, then I agree. If not, then you are > assuming that g is the same as at the time and location where > it was last calibrated. Yes. Just as I said. > > If, for example, you take a balance and spring scale to the moon, > you will find that the balance indicates the same mass as it > would on earth, but the spring scale, previously calibrated on > earth, does not. If the spring scale has fixed gradations, > you usually only have the ability to shift the zero. That's bathroom scales. The scales that you buy and sell goods on have multiple calibration points, electronically controllable. They use load cells which are a kind of spring.
From: rabid_fan on 18 May 2010 15:04 On Tue, 18 May 2010 10:35:08 +0100, Martin Brown wrote: > > Mass has proved the hardest of M,L & T to connect directly to > fundamental processes in nature and at the moment 1kg is still defined > as a reference lump of platinum metal in Paris. However, the latest > advances in ion cyclotron mass spectrometry look like they will provide > a means to define mass measurement in similar terms to L and T. >> Various methods to re-define the kilogram in terms of fundamental processes are presented here: http://en.wikipedia.org/wiki/Kilogram#Proposed_future_definitions The current standard, which is about 200 years old, is quite ridiculous due to the extreme variance of the standard masses.
From: Martin Brown on 18 May 2010 15:18 On 18/05/2010 10:58, Androcles wrote: > You should be made aware that you are conversing with a miserable > fuckwitted bigot called Martin Brown. His opinions will not enlighten > you at all, and nor will anyone's opinion. Opinions are like arseholes, > everybody has one and they all stink. Contrary to Brown's opinion, > Androcles has not voiced any opinion on matter. Androcles is a foul mouthed third rate netkook with delusions of adequacy. His knowledge of physics is very dodgy. CAVEAT EMPTOR! Regards, Martin Brown > "Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message > news:hbtIn.10099$7d5.7034(a)newsfe17.iad... >> On 17/05/2010 02:46, Angelo wrote: >>> On 17 Mag, 03:21, "Androcles"<Headmas...(a)Hogwarts.physics_z> wrote: >>>> "Angelo"<patri...(a)libero.it> wrote in message >>>> >>>> news:30514610-9062-465b-a4a9-14caf0227187(a)l18g2000vbn.googlegroups.com... >>>> >>>> On 15 Mag, 02:30, "hanson"<han...(a)quick.net> wrote: >>> >>> [snip] >>> >>>> Dear Hanson, (dear all), >>>> >>>> I share and sincerely appreciate all you said above >>>> and think to recognize the original (new for most) >>>> significance you pointed out (thanks, sincerely). >>>> >>>> Anyway, I'm personally convinced that N_A should >>>> be more appropriately named 'amount of substance' >>>> and should have physical dimensions of "particle/mole" >>>> where 'particle' may be atoms or molecules, in the >>>> simplest cases. >>>> >>>> Sorry for this adding that isn't in line with your main >>>> theme (I thought to take just an advantage to express >>>> that opinion of mine here). >>>> >>>> Could I have your valuable opinion(s)? >>>> >>>> Best regards, >>>> Angelo >>>> ==================================== >>>> Anyway, I'm impersonally convinced that 'substance' should >>>> be more appropriately named 'flubber' since nobody can tell >>> >>> Sorry, I have some difficulties as to regards at a >>> disambiguation of the term 'flubber' (please consider >>> that I'm not a native English speaker). >> >> You should be made aware that you are conversing with a netkook called >> Androcles. His opinions will not enlighten you at all. >> >> As far as we can tell gravitational attraction is consistent with the >> inertial mass of objects irrespective of their composition. The >> extention of the Eotvos experiment to different high purity materials >> by Roll, Krotov & Dicke supports the hypothesis that to a very good >> approximation inertial mass is a sensible measure. >> >> Androcles invents his "flubber" only to confuse you. >> >> The OP might find Wiki on Eotvos helpful >> >> http://en.wikipedia.org/wiki/E%C3%B6tv%C3%B6s_experiment >> >> And also the equivalence principle - a basic explanation online at: >> >> http://www.physicsdaily.com/physics/Equivalence_principle >> >> Mass has proved the hardest of M,L & T to connect directly to >> fundamental processes in nature and at the moment 1kg is still defined >> as a reference lump of platinum metal in Paris. However, the latest >> advances in ion cyclotron mass spectrometry look like they will >> provide a means to define mass measurement in similar terms to L and T. >>> >>>> me what matter or mass is. Valuable opinion given. >>> >>> Thank you for your valuable opinion, but you yourself >>> (I think) can realise that this is of no use for me as it >>> stands. >> >> It is no use to anybody. >> >> Regards, >> Martin Brown >
From: Androcles on 18 May 2010 15:23
"Martin Brown" <|||newspam|||@nezumi.demon.co.uk> wrote in message news:sKBIn.7612$%u7.5241(a)newsfe14.iad... > On 18/05/2010 10:58, Androcles wrote: >> You should be made aware that you are conversing with a miserable >> fuckwitted bigot called Martin Brown. His opinions will not enlighten >> you at all, and nor will anyone's opinion. Opinions are like arseholes, >> everybody has one and they all stink. Contrary to Brown's opinion, >> Androcles has not voiced any opinion on matter. > > Androcles is a foul mouthed third rate netkook with delusions of adequacy. > His knowledge of physics is very dodgy. CAVEAT EMPTOR! > > Regards, > Martin Brown Brown is fuckwitted troll hell-bent on a flame war, he cannot argue logically without resorting to insult. Disregards, Androcles. |