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Message: [QUOTE="cntrlwagdnr, post: 261236, member: 9346"] NASA does not use imperial units these days - no one does for that kind of scientific work. In fact, SI units (as opposed to"metric") are much more convenient and easy to use for that kind of thing, plus being less prone to making mistakes. SI is a different and more technically accurate standard than "metric", though it is a type of metric system. SI/metric units are based on natural principles - not arbitrary things like the length of the King's thumb!! Either are much less confusing for scientific and engineering calculations without the need for such odd units as Poundals to deal with. I grew up doing my engineering degree right around the time the UK started converting (lived in the USA since 1979, though). So we did both in college. I always found it easier when using imperial units, to convert to SI, do the calculations and convert the answer back at the end. Unfortunately most people do not know the different between force (weight) and mass, which really confuses the issues. For example, 1 kilogram is a measurement of mass and accurately describe a quantity of material. An imperial pound is also technically a measure of mass - not weight! The weight of 1 kilogram of material is the force it exerts (on a scale for example) under gravity - which can vary - thus it is not an accurate measure of how much you have. A poundal is simlarly the force or weight exerted by 1 lb of mass under gravity. So, all our measuring of produce by "weight" in lbs or kgs is really BS.... depending on the type of scale used. A balance scale that compares to known masses is in fact accurate, because it takes gravity out of the equasion - anywhere - even on the moon. Are you all confused now? You should be. But for most of our everday ativities, it doesn't really matter. The reason we did not fully convert to SI in the USA is due to a number of factors, mainly cost, inertia of change and resistiance by the population in general. You know, the same reasons the Brits obstinantly stick to driving on the wrong side of the road.... And, BTW, the US system is not the same as the old British imperial system. Close, but no banana. Most diferences are insignifacnt in the intereference level - except for the ton. A British ton (long ton) is equivalent to 2,200 lbs, whereas a US ton (short ton) is equivalent to 2,000 lbs. A Metric/SI tonne is in the middle but closer to a British ton. [/QUOTE]

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