Systems of Units
1 SYSTEMS OF UNITS Foot‐Pound‐Second (FPS) System Since long, the foot-pound-second (fps) system of units has been used to measure dimensions and quantities of material. The fundamental units are the foot for length, the pound for weight, and the second for time. The FPS system has two variants, known as the American version and the Imperial version. Now-a-days none of the systems is being used by scientists (after implementation of SI units). The International System of Units (SI) is preferred because it is simple and convenient. However, FPS units are still used to some extent by the general public, especially in the United States and in India also. Units of Length There are different units such as thou, inch, hand, foot, yard, rod, pace, mile, furlong, fathom, etc. used to measure length. However, the conversion factors are not simple. Thou One thousandth of an inch is called thou. In the United States it is called mil. The plural of thou is thou’ and of mil is ‘mils’. Inch An inch was originally defined as the width of a man's thumb, but later on it was defined as the length of three barleycorns placed end to end. The word inch comes from the Latin word for one-twelfth (uncia). The Romans, when invaded in the year 43, brought the concept of the 12 inch- foot to England and since then it had been used. Earlier the inch was subdivided into halves, quarters, eighths, sixteenths, and other powers of 1 2 Elementary Pharmaceutical Calculations two; and also into hundredths (as in the caliber of fire-arms) or thousandths (called thou in the UK and mils in the US).
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