The metric system sucks
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From: Andrew Usher on 5 Feb 2010 21:29 On Feb 4, 9:20 pm, Mark Borgerson <mborger...(a)comcast.net> wrote: > > Well, yes, technically. But if you used a weight measured with a scale > > (any type) the correction does come into account. > > That's not necessarily true either. If you are weighing iron > cannonballs on a balance scale using iron weights, no correction > is necessary. The same holds true on a balance scale whenever > the item and weights are of equal density. If the weights are > properly calibrated for their mass in vacuo, you will get > the proper in-vacuo weight of the cannonball. Yes, but balances are almost obsolete. When measuring force as modern scales do, the full correction is needed. > > > > Of > > > > course it changes with temperature as well; it's rather fortunate that > > > > water has a much lower thermal expansion than any other liquid at > > > > normal temperatures. > > Except for mercury, of course. Mercury has a coefficient of thermal > expansion of 18e-5, while water is 21e-5. Given that low coefficient > I suppose that mercury was used in thermometers, not because it > was the best expansion medium, but because of low vapor pressures > and high visibility. More so, actually, because the expansion of mercury (like most metals) is very uniform with temperature, so that thermometers could be divided on a linear scale and be fairly accurate. Also the very wide temperature range - mercury freezes only at -38 F, and does not decompose at the highest temperatures. Finally the thermal expansion of mercury is much lower than that of organic liquids, and the stem correction is proportional to it. The thermal expansion of water, on the other hand, goes from -5e-5 at freezing to 44e-5 at boiling (per degree F). > > > (unless, of course, you go below 32F! ;-) > > > No. That's negative thermal expansion! > > Not really---ice has a coefficient of thermal expansion quite different > from the volume change with the phase change. When you cool water to make ice, it expands. That's the reverse of normal, and so can be called negative, I would say. Yes, ice itself has a positive expansion. Andrew Usher
From: Andrew Usher on 5 Feb 2010 21:35 On Feb 4, 8:11 pm, Bill Owen <w...(a)jpl.nasa.gov> wrote: > > Actually, I've long thought decimal time wouldn't be a bad idea. But > > on the other hand, the fact that everyone works with the different > > units of time shows that non-decimal units are not really confusing to > > common people, unlike what metric propaganda says. (And if they were > > consistent, they would decimalise time - and angle, which is still > > worse, as I explained in Section V of my essay.) > > This was in fact tried (for time, for a time) during the French Revolution: > > http://en.wikipedia.org/wiki/French_Republican_Calendar > > http://en.wikipedia.org/wiki/Decimal_time Well decimalising the calendar (units larger than a day) is silly, because the year is not a round number of days and can't be. But decimalising the clock (units shorter than a day) is sound. I've thought we could have 1000 minutes in a day, and no other units. 25 and 50 minutes would essentially replace the half hour and hour for measuring the duration of things. Very short times could be either decimals of a minute, or in (old) seconds which would have to be retained anyway for science. > The closest they've come to decimalizing angles is the "grad," which is > 1/100 of a right angle. That is the most natural decimalisation, I think. Andrew Usher
From: Andrew Usher on 5 Feb 2010 21:40 On Feb 4, 8:22 pm, William Hamblen <william.hamb...(a)earthlink.net> wrote: > >Pardon me, but what do you mean here? How would you get the density of > >water in pounds per cubic foot? > > Weigh on a balance? BTW, a cubic foot of water is about 62.4 pounds. No, they've measured it to much greater accuracy than one could oneself. The point is that you would look it up if need be, and if it's only given in metric you would have to convert (but only once, of course). > The pound is a unit of mass (2.205 pounds per Kg, roughly). There is > a pound force that has the same name but is 4.45 newtons, roughly. Yes, at least you got that right. There's a ridiculous belief in the US that the pound is (only) a unit of force. Andrew Usher
From: Andrew Usher on 5 Feb 2010 21:48 On Feb 4, 8:36 pm, William Hamblen <william.hamb...(a)earthlink.net> wrote: > >What system do geologists use? There was an argument in > >sci.physics about 12 years ago w.r.t. which system was > >preferred in doing physics work. > > Old physicists used cgs, young physicists use SI. In geological fields, to answer his question, feet and inches were extensively used to the 1960s. That's one of the things I had in mind. And physicists quite often use natural units or no units in theory. Andrew Usher
From: Bart Goddard on 5 Feb 2010 22:05
adamk <adamk(a)adamk.net> wrote in news:752291235.119340.1265419992761.JavaMail.root(a)gallium.mathforum.org: > Wrong. Chinese and Hindi are the most spoken. Not wrong. If you google and wiki about, you'll see that the numbers of speakers of various languages vary widely. You may fail to see, however, that the number rarely include India among English-speaking nation, yet English is the official language of India. Once you add the population of India to that number (which you should for the purposes of this discussion, which is about trades between nations) then English slaughters all other languages. B. -- Cheerfully resisting change since 1959. |