For example, the free software movement offers a command line utility GNU units for Linux and Windows.Ĭalculation involving non-SI Units There are many standalone applications that offer the thousands of the various units with conversions. They are found in the function libraries of applications such as spreadsheets databases, in calculators, and in macro packages and plugins for many other applications such as the mathematical, scientific and technical applications. Thus, it is found that 5 kilometers per second is equal to 5000 meters per second. The symbols km, m, and s represent kilometer, meter, and second, respectively.ĥ km s ⋅ 1000 m 1 km = 5000 ⋅ m s ⋅ 1 = 5000 m s The following example demonstrates how the unity bracket method is used to convert the rate 5 kilometers per second to meters per second. So as long as the numerator and denominator of the fraction are equivalent, they will not affect the value of the measured quantity. Also, if the numerator and denominator of a fraction are equal to each other, then the fraction is equal to one. Because of the identity property of multiplication, the value of a quantity will not change as long as it is multiplied by one. The unity bracket method of unit conversion consists of a fraction in which the denominator is equal to the numerator, but they are in different units. Nominal values are sometimes allowed and used.Ī conversion factor is used to change the units of a measured quantity without changing its value. It sometimes involves a slightly different configuration, or size substitution, of the item. It changes the measurement to convenient and workable numbers and units in the new system. It does not involve changing the physical configuration of the item being measured.īy contrast, a hard conversion or an adaptive conversion may not be exactly equivalent. This is sometimes called soft conversion. Some conversions from one system of units to another need to be exact, without increasing or decreasing the precision of the first measurement. Historical definitions of the units and their derivatives used in old measurements e.g., international foot vs.The intended use of the measurement including the engineering tolerances.The number of significant figures of the measurement.The statistical confidence interval or tolerance interval of the initial measurement.The precision and accuracy of measurement and the associated uncertainty of measurement.Engineering judgment may include such factors as: This may be governed by regulation, contract, technical specifications or other published standards. The process of conversion depends on the specific situation and the intended purpose. See also: Dimensional analysis Process overview 2.24 Electromotive force, electric potential difference.
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