Centimetre
From Wikipedia, the free encyclopedia
| SI units | |
|---|---|
| 10×10−3 m | 10 mm |
| US customary / Imperial units | |
| 32.81×10−3 ft | 0.39370 in |
A centimetre (American spelling: centimeter, symbol cm) is a unit of length in the metric system, equal to one hundredth of a metre, which is the current SI base unit of length. Centi is the SI prefix for a factor of 10 − 2.[1] Hence a centimetre can be written as 10×10 − 3 m (engineering notation) or 1 E-2 m (scientific E notation) — meaning 10 × 1 mm or 1 m / 100 respectively. The centimetre is the base unit of length in the now deprecated centimetre-gram-second system of units.
Though for many physical quantities, SI prefixes for factors of 103 - like milli and kilo - are often preferred by technicians, the centimetre remains a practical unit of length for many everyday measurements. A centimetre is approximately the width of the fingernail of an adult person.
The centimeter is the distance light travels through a vacuum in 
second.
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[edit] Equivalence to other units of length
1 centimetre is equal to:
- 0.01 metres, which can be represented by 1.00 E-2 m (1 metre is equal to 100 centimetres)
- about 0.393700787401575 inches (1 inch is equal to 2.54 centimetres exactly) [2]
1 cubic centimetre is equal to 1 millilitre, under the current SI system of units.
[edit] Uses of centimetre
In addition to its use in the measurement of length, the centimetre is used:
- sometimes, to report the level of rainfall as measured by a rain gauge [3]
- in the CGS system, the centimetre is used to measure capacitance, where 1 cm of capacitance = 1.113×10 − 12 Farad [4]
- in Canadian maps, centimetres are used to make conversions from map scale to real world scale (kilometres)
[edit] Unicode symbols
For the purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has symbols for: [5]
- centimetre (㎝) - code 339D
- square centimetre (㎠) - code 33A0
- cubic centimetre (㎤) - code 33A4
They are useful only with East Asian fixed-width CJK fonts, because they are equal in size to one Chinese character.
[edit] See also
- 1 E-2 m
- SI
- SI prefix
- Metric system
- Orders of magnitude (length)
- Conversion of units, for comparison with other units of length
[edit] References
- ^ BIPM - SI prefixes
- ^ Inch - from Eric Weisstein's World of Physics
- ^ Rain Measurement, Rain Gauge, Wireless Rain Gauge, Rain Gage, Rain Gauge Data
- ^ Capacitance - from Eric Weisstein's World of Physics
- ^ [1] CJK Compatibility excerpt from The Unicode Standard, Version 4.1.
[edit] External links
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