ISO 31-1
In this article, we are going to deeply explore the topic of ISO 31-1, a topic that has captured the attention of many people in recent years. ISO 31-1 has generated great interest and debate in different areas, from science to politics, including popular culture. Throughout this article, we will examine the different aspects of ISO 31-1, from its origins and evolution, to its impact on today's society. Additionally, we will discuss the opinions and perspectives of experts on the topic, as well as the personal experiences of those who have been directly involved with ISO 31-1. This article aims to provide readers with a broad understanding of ISO 31-1 and encourage critical reflection on this topic that is so relevant today.
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ISO 31-1 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 It was superseded in 2006 by ISO 80000-3.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 m2⁄m2 = 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 | m2 | The units are (1 a = 100 m2) and hectare (1 ha = 100 a) are used for agrarian areas. | |
| volume | V | cubic metre | m3 | ||
| litre | L, l | 1 L = 1 dm3 | 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⁄s2 | 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⁄s2 | 1 g = 9.80665 m⁄s2 | |
| 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.
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