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Conversions between units in the metric system are defined by their prefixes (for example, 1 kilogram = 1000 grams, 1 milligram = 0.001 grams) and are thus not listed in this article. Exceptions are made if the unit is commonly known by another name (for example, 1 micron = 10 −6 metre).
Sizes that may interchange, depending on the precision needed, include 2 mm (close to 5 ⁄ 64 inch (1.98 mm)), 4 mm (close to 5 ⁄ 32 inch (3.97 mm)) and 8 mm (close to 5 ⁄ 16 inch (7.94 mm)). In reality, a wrench with a width across the flats of exactly 15 mm would fit too tightly to use on a bolt with a width across the flats of 15 mm.
1 km 2 means one square kilometre, or the area of a square of 1000 m by 1000 m. In other words, an area of 1 000 000 square metres and not 1000 square metres. 2 Mm 3 means two cubic megametres, or the volume of two cubes of 1 000 000 m by 1 000 000 m by 1 000 000 m, i.e. 2 × 10 18 m 3, and not 2 000 000 cubic metres (2 × 10 6 m 3).
The unit prefixes are always considered to be part of the unit, so that, e.g., in exponentiation, 1 km 2 means one square kilometre, not one thousand square metres, and 1 cm 3 means one cubic centimetre, not one hundredth of a cubic metre. In general, prefixes are used with any metric unit, but may also be used with non-metric units.
Comparison of 1 square metre with some Imperial and metric units of area. The square metre (international spelling as used by the International Bureau of Weights and Measures) or square meter (American spelling) is the unit of area in the International System of Units (SI) with symbol m 2. [1] It is the area of a square with sides one metre in ...
For example, 1 m/s = 1 m / (1 s) is the coherent derived unit for velocity. [ 1 ] : 139 With the exception of the kilogram (for which the prefix kilo- is required for a coherent unit), when prefixes are used with the coherent SI units, the resulting units are no longer coherent, because the prefix introduces a numerical factor other than one.
A metric ISO screw thread is designated by the letter M followed by the value of the nominal diameter D (the maximum thread diameter) and the pitch P, both expressed in millimetres and separated by a dash or sometimes the multiplication sign, × (e.g. M8-1.25 or M8×1.25). If the pitch is the normally used "coarse" pitch listed in ISO 261 or ...
The solar flux unit is a unit of spectral irradiance equal to 10 −22 W⋅m −2 ⋅Hz −1 (100 yW⋅m −2 ⋅Hz −1). The nox (nx) is a unit of illuminance equal to 1 millilux (1 mlx). The nit (nt) is a unit of luminance equal to one candela per metre squared (1 cd⋅m −2). The lambert (L) is a unit of luminance equal to 10 4 /π cd⋅m ...