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Systems of measurement

Systems of measurement

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Systems of measurement

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  1. Systems of measurement

  2. Index • History……………………………………………………..1 • Metric System…………………………………………..2 • US Costumary Units………………………………….3 • Units of currency……………………………………….4 • Conversion Tables………………………………………5

  3. History • Although we might suggest that the Egyptians had discovered the art of measurement, it is only with the Greeks that the science of measurement begins to appear. The Greek's knowledge of geometry, and their early experimentation with weights and measures, soon began to place their measurement system on a more scientific basis. By comparison, Roman science, which came later, was not as advanced...[1] • The French Revolution gave rise to the metric system, and this has spread around the world, replacing most customary units of measure. In most systems, length (distance), weight, and time are fundamental quantities; or as has been now accepted as better in science, the substitution of mass for weight, as a better more basic parameter. Some systems have changed to recognize the improved relationship, notably the 1824 legal changes to the imperial system. • Later science developments showed that either electric charge or electric current must be added to complete the minimum set of fundamental quantities by which all other metrological units may be defined. Other quantities, such as power, speed, etc. are derived from the fundamental set; for example, speed is distance per unit time. Historically a wide range of units was used for the same quantity, in several cultural settings, length was measured in inches, feet, yards, fathoms, rods, chains, furlongs, miles, nautical miles, stadia, leagues, with conversion factors which were not simple powers of ten or even simple fractions within a given customary system. • Nor were they necessarily the same units (or equal units) between different members of similar cultural backgrounds. It must be understood by the modern reader that historically, measurement systems were perfectly adequate within their own cultural milieu, and the understanding that a better more universal system (based on more rationale and fundamental units) only gradually spread with the maturation and appreciation of the rigor characteristic of Newtonian physics. Moreover, changing a measurement system has real fiscal and cultural costs as well as the advantages that accrue from replacing one measuring system with a better one. • Once the analysis tools within that field were appreciated and came into widespread use in the emerging sciences, especially in the applied sciences like civil and mechanical engineering, pressure built up for conversion to a common basis of measurement. As people increasingly appreciated these needs and the difficulties of converting between numerous national customary systems became more widely recognised there was an obvious justification for an international effort to standardise measurements. The French Revolutionary spirit took the first significant and radical step down that road. • In antiquity, systems of measurement were defined locally, the different units were defined independently according to the length of a king's thumb or the size of his foot, the length of stride, the length of arm or per custom like the weight of water in a keg of specific size, perhaps itself defined in hands and knuckles. The unifying characteristic is that there was some definition based on some standard, however egocentric or amusing it may now seem viewed with eyes used to modern precision. Eventually cubits and strides gave way under need and demand from merchants and evolved to customary units. • In the metric system and other recent systems, a single basic unit is used for each fundamental quantity. Often secondary units (multiples and submultiples) are used which convert to the basic units by multiplying by powers of ten, i.e., by simply moving the decimal point. Thus the basic metric unit of length is the metre; a distance of 1.234 m is 1234.0 millimetres, or 0.001234 kilometers.

  4. Metric System • The metric system is an international decimalised system of measurement that was originally based on the mètre des archives and the kilogramme des archives introduced by France in 1799. Over the years, the definitions of the metre and kilogram have been refined and the metric system extended to incorporate many more units. Although a number of variants of the metric system emerged in the late nineteenth and early twentieth centuries the term is now often used as a synonym for "SI" or the "International System of Units" (French: "Système international d'unités") - the official system of measurement in almost every country in the world. • Only a handful of countries in the world have not adopted the metric system, with sources generally including Liberia, Burma, and the United States in this very rare category (see map in "Usage around the world," below). The United States is the only industrialised country that does not use the metric system as its official system of measurement, although the metric system has been officially sanctioned for use there since 1866. Although the United Kingdom committed to officially adopting the metric system for many measurement applications, it is still not in universal use there and the customary imperial system is still in common and widespread use. • Although the originators intended to devise a system that was equally accessible to all, it proved necessary to use prototype units under the custody of government or other approved authorities as standards. Until 1875 control of the prototype units of measure was maintained by the French Government when it passed to an inter-governmental organisation – the Conférencegénérale des poids et mesures (CGPM). It is now hoped that the last of these prototypes can be retired by 2014. • From its beginning, the main feature of the metric system was the standard set of inter-related base units and a standard set of prefixes in powers of ten. These base units are used to derive larger and smaller units and replaced a huge number of unstandardised units of measure that existed previously. While the system was first developed for commercial use, its coherent set of units made it particularly suitable for scientific and engineering purposes. • The uncoordinated use of the metric system by different scientific and engineering disciplines, particularly in the late 19th century, resulted in different choices of fundamental units, even though all were based on the same definitions of the metre and the kilogram. During the 20th century, efforts were made to rationalise these units and in 1960 the CGPM published the International System of Units which, since then, has been the internationally recognised standard metric system.

  5. US Costumary Units • Jump to: navigation, search • United States customary units are a system of measurements commonly used in the United States. Many U.S. units are virtually identical to their imperial counterparts, but the U.S. customary system developed from English units used in the British Empire before the system of imperial units was standardized in 1824. Several numerical differences from the imperial system are present. • The vast majority of U.S. customary units have been defined in terms of the meter and the kilogram since the Mendenhall Order of 1893 (and, in practice, for many years before that date).[1] These definitions were refined by the international yard and pound agreement of 1959. • According to the CIA Factbook, the United States is one of three countries (the others being Liberia and Burma/Myanmar) that has not adopted the International System of Units (SI) metric system as their official system of weights and measures. The U.S. does not primarily use SI units in its commercial activities, although they are standard in science, medicine, and government (including the U.S. Armed Forces), as well as many sectors of industry.

  6. Units of currency • A unit of measurement that applies to money is called a unit of account. This is normally a currency issued by a country or a fraction thereof; for instance, the US dollar and US cent (1⁄100 of a dollar), or the euro and euro cent. • ISO 4217 is the international standard describing three letter codes (also known as the currency code) to define the names of currencies established by the International Organization for Standardization (IOS). • [edit] Historical systems of measurement • Main article: History of measurement • Throughout history, many official systems of measurement have been used. While no longer in official use, some of these customary systems are occasionally used in day to day life, for instance in cooking. • [edit] Afroasia • Arabic[4] • Egyptian • Hebrew • Maltese • Mesopotamian • [edit] Asia • See also: history of measurement systems in India • Chinese • Hindu • Japanese • Persian • Taiwanese • Tamil • Thai • Vietnamese • Nepalese • [edit] Europe • Danish • Dutch • English • Finnish • French (now) • French (to 1795) • German • Greek • Norwegian • Polish • Portuguese • Roman • Romanian • Russian • Scottish • Spanish • Swedish • Tatar • Welsh

  7. Conversion Tables • Approximate conversion of units • Conversion of units

  8. Conclusion • The system of measurement isreallyimportantto the daily life. • A system of measurement is a set of units which can be used to specify anything which can be measured and were historically important, regulated and defined because of trade and internal commerce.