Encyclopaedia of Scientific Units, Weights and Measures Their SI Equivalences and Origins
FrancËois Cardarelli Encyclopaedia of Scientific Units, Weights and Measures Their SI Equivalences and Origins English translation by M.J. Shields, FIInfSc, MITI 13 Other Systems 3 of Units Despite the internationalization of SI units, and the fact that other units are actually forbidden by law in France and other countries, there are still some older or parallel systems remaining in use in several areas of science and technology. Before presenting conversion tables for them, it is important to put these systems into their initial context. A brief review of systems is given ranging from the ancient and obsolete (e.g. Egyptian, Greek, Roman, Old French) to the relatively modern and still in use (e.g. UK imperial, US customary, cgs, FPS), since a general knowledge of these systems can be useful in conversion calculations. Most of the ancient systems are now totally obsolete, and are included for general or historical interest. 3.1 MTS, MKpS, MKSA 3.1.1 The MKpS System The former system of units referred to by the international abbreviations MKpS, MKfS, or MKS (derived from the French titles meÁtre-kilogramme-poids-seconde or meÁtre-kilo- gramme-force-seconde) was in fact entitled SysteÁme des MeÂcaniciens (Mechanical Engi- neers' System). It was based on three fundamental units, the metre, the second, and a weight unit, the kilogram-force. This had the basic fault of being dependent on the acceleration due to gravity g, which varies on different parts of the Earth, so that the unit could not be given a general definition. Furthermore, because of the lack of a unit of mass, it was difficult, if not impossible to draw a distinction between weight, or force, and mass (see also 3.4).
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