ISO 31-1
Part of international standard ISO 31
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ISO 31-1 [1] is the part of international standard ISO 31 that defines names and symbols for quantities and units related to space and time . It was superseded in 2006 by ISO 80000-3 .
Definitions
Its definitions include:
Quantity | Unit | Remarks | |||
---|---|---|---|---|---|
Name | Symbol | Name | Symbol | Definition | |
angle
,
(plane angle) |
α, β, γ, θ, φ | radian | rad | 1 rad = 1 m ⁄ m = 1 | |
degree | ° | 1° = π ⁄ 180 rad | There is no space between the number and these superscript-style unit symbols. Decimal subdivision of degrees is preferable (i.e., 12.5° instead of 12°30′) | ||
minute | ′ | 1′ = ( 1 ⁄ 60 )° | |||
second | ″ | 1″ = ( 1 ⁄ 60 )′ | |||
solid angle | Ω | steradian | sr | 1 sr = 1 m 2 ⁄ m 2 = 1 | |
length | l, L | metre | m | The metre is the length of the path travelled by light in vacuum during a time interval of 1 ⁄ 299 792 458 of a second; see speed of light | |
breadth | b | ||||
height | h | ||||
thickness | d, δ | ||||
radius | r, R | ||||
diameter | d, D | ||||
length of path , (linear) displacement vector | s, s | ||||
distance | d, r | ||||
cartesian coordinates | x, y, z | ||||
radius of curvature | ϱ | ||||
curvature | ϰ | reciprocal metre | m −1 | ||
area | A | square metre | m 2 | The units are (1 a = 100 m 2 ) and hectare (1 ha = 100 a) are used for agrarian areas. | |
volume | V | cubic metre | m 3 | ||
litre | L, l | 1 L = 1 dm 3 | The capital L is preferred as the small l can be indistinguishable from the number 1 in some fonts. | ||
time , time interval , duration | t | second | s | The second is the duration of 9 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium -133 atom | Representations of time of day are defined in ISO 8601 . |
minute | min | 1 min = 60 s | |||
hour | h | 1 h = 60 min = 3 600 s | |||
day | d | 1 d = 24 h = 1 440 min = 86 400 s | |||
angular velocity | ω | radian per second | rad ⁄ s | ω= dφ ⁄ dt | |
angular acceleration | α | radian per second squared | rad ⁄ s 2 | α= dω ⁄ dt | |
velocity |
v
(general symbol),
v (velocity vector), c (propagation speed of waves), u , v , w (components of a velocity c ) |
metre per second | m ⁄ s | ||
kilometre per hour | km ⁄ h | ||||
acceleration , acceleration vector | a, a | metre per second squared | m ⁄ s 2 | 1 g = 9.80665 m ⁄ s 2 | |
acceleration of free fall , acceleration due to gravity | g |
Annex A
Annex A of ISO 31-1 lists units of space and time based on the foot , pound , and second .
Annex B
Annex B lists some other non-SI units of space and time, namely the gon , light year , astronomical unit , parsec , tropical year , and gal .
References
- ↑ "ISO 31-1:1992" . ISO . Retrieved 2023-02-07 .
International standards |
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|
---|---|---|
Obsolete standards | ||
Time in physics | ||
Horology | ||
Calendar | ||
Archaeology and geology | ||
Astronomical chronology | ||
Other units of time | ||
Related topics |
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