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Am Sun, 02 May 2004 11:42:43 -0500 schrieb "Herb Schaltegger":
For a normal person it is almost impossible to understand all these interesting topics when it is full of gallons, feets and psi's instead of litres, meters and Pascals "Normal person", huh? You mean, some sort of "units snob?" Well, since a good part of these "interesting topics" all use Imperial measurements (the American part, of course), wouldn't it behoove you to learn a few simple conversions so you can understand the discussion? After all, a good many of us did so and can work fairly easily in either system. No, the problem with MANY (if not most) non-metric units is, that there are often several localized versions of them - If you say (for example) mile, pound or gallon, you can _never_ be absolutely, 100% sure, which particular type of mile, pound or gallon is actually meant - especially for people that are grown up in regions, where the reflective use of these units has not been teached. Strict use of metric (SI) units avoids ESPECIALLY THAT problem. And there is the second problem of many redundant units - there is absolutely no real need for a hundred or more different units for mass, force, temperature, length (area/volume) and so on, for each of are needed conversion factors that are _not_ simply powers of ten. In SI there are only a very small couple of them. cu, ZiLi aka HKZL (Heinrich Zinndorf-Linker) -- /"\ ASCII Ribbon Campaign \ / http://zili.de X No HTML in / \ email & news |
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"Hans" wrote in message ...
I agree. For a normal person it is almost impossible to understand all these interesting topics when it is full of gallons, feets and psi's instead of litres, meters and Pascals That's a rather provincial notion don't you think? That only "normal" people use SI units and you have to be abnormal to use feet or gallons. Where's the love of diversity? Where's the basic level of respect for other cultures and other methods of doing things? |
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In article ,
"Heinrich Zinndorf-Linker (zili@home)" wrote: No, the problem with MANY (if not most) non-metric units is, that there are often several localized versions of them - If you say (for example) mile, pound or gallon, you can _never_ be absolutely, 100% sure, which particular type of mile, pound or gallon is actually meant - especially for people that are grown up in regions, where the reflective use of these units has not been teached. Strict use of metric (SI) units avoids ESPECIALLY THAT problem. No, yourself. In the context of sci.space.history and the history of Project Apollo, the units questioned by the earlier poster "gallons, feets and psi's" are all easily understood - as is the poster's snobbishness and disdain for learning anything other than the system he is most comfortable with. There are no "localized versions" at issue with any of them vis a vis Apollo. The only definitions for these units anyone need concern him- or herself with in this discussion are the American ones. For any other SI-snobs out there too lazy to look things up yourselves, here are some basic conversions to keep you happy: 1 U.S. gallon = 3.79 liters 1 foot = 12 inches = 0.305 meters 1 inch = 2.54 centimeters 1 psi (pound per square inch) = 6.89 kilopascals 1 lbf (pound force) = 4.45 newtons And there is the second problem of many redundant units - there is absolutely no real need for a hundred or more different units for mass, force, temperature, length (area/volume) and so on, for each of are needed conversion factors that are _not_ simply powers of ten. In SI there are only a very small couple of them. Hate to break it to you, but when you start getting down to the nitty gritty of the physics, the fundamental constants of nature don't give a rat's ass about powers of ten. Doing the math itself in most engineering applications is a hell of a lot harder than looking up a silly conversion factor to change units at the end. -- Herb Schaltegger, B.S., J.D. Reformed Aerospace Engineer Columbia Loss FAQ: http://www.io.com/~o_m/columbia_loss_faq_x.html |
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"Heinrich Zinndorf-Linker (zili@home)" wrote in message ... | | No, the problem with MANY (if not most) non-metric units is, that | there are often several localized versions of them Not when engineers use them. The English Engineering system is as rigidly defined as the Systeme Internationale. I'm not trying to trash SI, but the touted advantages are largely irrelevant in use. For example, the relationship between liter and kilogram seems wonderfully logical until you forget to take into account just under what precise (and largely arbitrary) conditions a kilogram and a liter of water can be considered equivalent. Silliness is not in the use of arbitrary units; it's in the use of units that are claimed to be consistent but are deceptively arbitrary anyway. If a liter of water is *really* 0.994 kilogram under the conditions of interest, then what good is it telling a student the SI system is consistent? Foolishness is conveying the *illusion* of consistency and then failing to deliver it. -- | The universe is not required to conform | Jay Windley to the expectations of the ignorant. | webmaster @ clavius.org |
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In article ,
Jay Windley wrote: I'm not trying to trash SI, but the touted advantages are largely irrelevant in use. For example, the relationship between liter and kilogram... Uh, what relationship between liter and kilogram? You are thinking of earlier versions of the metric system; SI defines no such relationship. -- MOST launched 30 June; science observations running | Henry Spencer since Oct; first surprises seen; papers pending. | |
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On 5/2/04 7:43 AM, in article , "Hans"
wrote: I agree. For a normal person it is almost impossible to understand all these interesting topics when it is full of gallons, feets and psi's instead of litres, meters and Pascals Another sad comment on the current capabilities of the "normal person". Or, you personally. Brett |
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"Herb Schaltegger" wrote in message ... Well, since a good part of these "interesting topics" all use Imperial measurements (the American part, of course), wouldn't it behoove you to learn a few simple conversions so you can understand the discussion? After all, a good many of us did so and can work fairly easily in either system. The only difficult thing for me would be the difference between gauge pressure and absolute pressure, but I learned that difference in high school so it's nothing now. |
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