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 . Hence a centimetre can
be written as (
engineering
notation) or (
scientific E notation) —
meaning or respectively,
centimetre-gram-second system of
units.
Though for many physical quantities,
SI
prefixes for factors of 10
^{3}—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.
Equivalence to other units of length
A carpenters' ruler with centimetre
divisions
1 centimetre is
equal to:
- 0.01 metre, which can be represented by 1.00
E-2 m (1 metre is equal to 100 centimetres)
- about 0.393700787401575 inch (1 inch is
equal to 2.54 centimetres)
1 cubic centimetre is equal to 1
millilitre,
under the current
SI system of units.
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
- in the CGS system, the centimetre is used to measure capacitance, where 1 cm of capacitance =
1.113×10^{-12} Farad
- in maps, centimetres are used to make conversions from map
scale to real world scale (kilometres)
- to represent second moment of areas (cm^4)
Unicode symbols
For the
purposes of compatibility with Chinese, Japanese and Korean (CJK) characters, Unicode has
symbols for:
- centimetre (㎝) - code 339D
- square centimetre (㎠) - code 33A0
- cubic centimetre (㎤) - code 33A4
They are only useful with East Asian fixed-width
CJK fonts, because they are equal in size to one Chinese
character.
See also
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.