I feel I need to take issue with assertion that grams and kilograms or millimeters and meters are different units. The unit is the kilogram and the meter. The prefixes only scale units in decimal multiples and submultiples (they are a replacement for formally writing out scientific notation).
Only the unit is coherent in calculations. When combined with a prefix, coherence is lost (except the kilogram, where the prefix is a part of the unit). It is true that essentially all engineering societies use the convention that all dimensions are millimeters unless otherwise noted (only they may appear as a "naked number" without an explicit unit). However, engineers calculate, and the coherent unit for length in calculations is the meter. One absolutely must be able to convert a prefixed unit to the basic unit and scientific notation. Every engineer will be using only millimeters on drawings and only meters in calculations, hence "converting" between them. I will grant that American schools go a bit overboard in how many nanometers are in a kilometer, and "extreme decimal shuffling;" however, one MUST be able to convert at least between the adjacent prefixes one is likely to encounter in the real world. Even in dividing or multiplying a recipe, one is likely to need to shift between grams and kilograms. I feel that the basic skill to shift between relevant prefixes is an essential metric skill, and for one to lack it, or to create a metrication policy which attempts to avoid it is a very poor form of metrication indeed. A person with a general education probably does not need to know every prefix from yotto to yocto, but perhaps from micro to mega, and a couple more depending on profession. However, if you insist people must not know more than one prefix for a given thing, then it is necessary to use only meters and kilograms to maintain a coherent set, as coherence is one of the most important attributes of the metric system (there is some discussion in 1.4 of SI Brochure). Where we may agree is that one must generally use "unitized" numbers, naked numbers can only be used with an absolutely rigid code of how to interpret them. ________________________________ From: Pat Naughtin <[email protected]> To: U.S. Metric Association <[email protected]> Sent: Sat, January 22, 2011 5:33:39 PM Subject: [USMA:49576] Re: More dumbing down via NPR As you know I have pointed out here previously that if you don't have a metrication policy then people will make up their own often providing two possible metric system units. This leads directly, in my opinion, to what the Heath brothers call "decision paralysis" where people do not have enough knowledge of the metric system to know what to do; so they revert to old pre-metric measuring words because they seem to be familiar (and not necessarily because they understand these either). Important examples are: * Human height where centimetres and metres are on offer as possible choices. This choice is promoted by schools who promote centimetres and the medical professions who promote metres for Body Mass Index (BMI). Given a choice many Australians say, "What's that in feet and inches?" * Baby masses where women are given a choice between grams and kilograms. Not knowing what to do with these, and not knowing that the use of kilograms is inherently unsafe for the health of the baby, their next question is "What's that in pounds and ounces?"; again putting the baby's health at even more serious risk. * The textile industries chose to use metres and centimetres as their preferred metric system units. These have then been divided into fractions such as half metres and quarter metres and (like the Apple Computer Company) into half centimetres and quarter centimetres. Given these choices a lot of women continue to use their old patterns in feet, inches, and yards and to train their daughters to do likewise. A few, such as fine artwork quilters, work in millimetres and the quality of their work shows the other quilters up remarkably. Insofar as the metrication of Australia is concerned, we were totally successful in areas that involved construction and engineering in all its forms (roads, electrical, construction, civil, environmental and so on) where the policy decision was made to use millimetres, ONLY. The metrication upgrade was quick easy and extremely economical (saving about 10 % of turnover for most companies). My estimate is that we are 90 % metric or more but we still have to work on the remainder. See http://www.metricationmatters.com/docs/CostOfNonMetrication.pdf It would be wise for the USA to look at Australian successes -- and failures -- as a guide to changing from "hidden metrication" to an honest an open "direct metrication". Done well the USA could again lead the world in honest and open measurement policies as they have done since the early 1780s. See http://www.metricationmatters.com/docs/MetricationTimeline.pdf and search for USA. Cheers, Pat Naughtin Geelong, Australia On 2011/01/23, at 08:21 , [email protected] wrote: I am listening to NPR and Atlanta Public Media. An Australian woman is describing her journey from Sydney to the protected reserve where aborigines live up north (closest large city is Darwin). > >The aborigine could be heard telling the woman that they had 10 liters of >water >just in case they break down, which was nice. But when the woman was >describing >the height of some things she could see while trraveling in the reserve, she >used "feet" rather than "meters" (not even saying the height n meters first). > >I'm quite sure the American producer asked her to convert to feet or else the >Aussie woman just assumed she needed to convert since she knew the program was >for an American audience. > >Too bad.... another chance to give Americans a clue that Australia is fully >metric was lost. > >Ezra > Pat Naughtin LCAMS Author of the ebook, Metrication Leaders Guide, see http://metricationmatters.com/MetricationLeadersGuideInfo.html Hear Pat speak at: http://www.youtube.com/watch?v=_lshRAPvPZY PO Box 305 Belmont 3216, Geelong, Australia Phone: 61 3 5241 2008 Metric system consultant, writer, and speaker, Pat Naughtin, has helped thousands of people and hundreds of companies upgrade to the modern metric system smoothly, quickly, and so economically that they now save thousands each year when buying, processing, or selling for their businesses. Pat provides services and resources for many different trades, crafts, and professions for commercial, industrial and government metrication leaders in Asia, Europe, and in the USA. Pat's clients include the Australian Government, Google, NASA, NIST, and the metric associations of Canada, the UK, and the USA. See http://www.metricationmatters.com/ to subscribe.
