ISO 80000-3

ISO 80000-3:2006 is an ISO standard entitled Quantities and units – Part 3: Space and time, superseding ISO 31-1 and ISO 31-2.^[1] It is a part of the group of standards called ISO/IEC 80000, which together form the International System of Quantities.

Contents list

The standard is divided into the following chapters:

• Foreword
• Introduction

1. Scope
2. Normative references
3. Names, symbols and definitions

• Annex A (informative) Units in the CGS system with special names
• Annex B (informative) Units based on the foot, pound, second, and some other related units
• Annex C (informative) Other non-SI units given for information, especially regarding the conversion factors

Names, symbols and definitions

Space and time

Space

ISO 80000-3:2006 assigns names and symbols to quantities and units of space and time, and defines these quantities and units. For example

Units of length, area and volume

• metre (symbol m): "length of the path travelled by light in vacuum during a time interval of 1/(299 792 458) of a second."

Other units of distance defined by the standard are the ångström (symbol Å) (10⁻¹⁰ m) and the nautical mile (1852 m). No symbol is given for the nautical mile.

The are (symbol a) is a unit of area equal to 100 square metres.

The litre (symbol L or l) is a unit of volume equal to 10⁻³ m³.

Units of angle

• radian
• degree of arc: π/180 radians
• minute of arc: 1/60 degrees of arc
• second of arc: 1/60 minutes of arc
• gon: π/200 rad

Quantities

• curvature: χ = 1/ρ, where ρ = radius of curvature
• area
• volume
• angle: α = s/r, where s = length of arc of a circle and r = radius of the circle
• solid angle

Time

ISO 80000-3:2006 assigns names and symbols to quantities and units of space and time, and defines these quantities and units. For example

Units of time, speed and acceleration

• second (symbol s): "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"

Other units of time defined by the standard include the minute (1 min = 60 s), the hour (1 h = 60 min) and the day (1 d = 24 h). The year (1 a = 365 d or 366 d) is defined in an informative annex.

• knot (symbol kn): one nautical mile per hour = 1852/3600 m/s ≈ 0.514 444 m/s.

Quantities

The standard acceleration of free fall is 9.806 65 m/s².

Logarithmic quantities and units

The bel and the neper are units of level. Level of a field quantity F is defined as ln(F/F₀ ) = 20 lg(F/F₀) dB. Level of a power quantity P is defined as (1/2) ln(P/P₀) = 10 lg(P/P₀) dB. The later ISO standard ISO 80000-1:2009 replaces the term field quantity with root-power quantity and deprecates field quantity.

Units of level defined by ISO 80000-3:2006 are

• neper: 1 Np = ln(e) = 1
• bel: 1 B = ln(sqrt(10)) Np
• decibel: 1 dB = 0.1 B

Annex A (informative)

The following CGS units are deprecated:

• The gal (CGS unit of acceleration, equal to 1 cm/s²)

Annex B (informative)

The following non-SI units are deprecated by the standard:

• The inch (Imperial unit of distance, equal to 25.4 mm)
• The foot (Imperial unit of distance, equal to 12 inches)
• The yard (Imperial unit of distance, equal to 3 feet)
• The mile (Imperial unit of distance, equal to 1760 yards)
• The acre (Imperial unit of area, equal to 4840 square yards)

Annex C (informative)

The following non-SI units are given for conversion. They are not deprecated by the standard

• Units of distance: light year (the distance travelled in one year by light in vacuum; 1 l.y. ≈ 9,460 730 × 10¹⁵ m), astronomical unit (the mean distance of the Earth from the Sun, 1 ua ≈ 1,495 978 706 91(30) × 10¹¹ m), parsec (the distance at which 1 ua subtends an angle of 1 " (second of arc); 1 pc ≈ 206 264,8 ua ≈ 30,856 78 × 10¹⁵ m)
• Units of time: year (a), equal to either 365 days or 366 days

See also

• ISO 80000-1 General
• ISO 80000-2 Mathematical signs and symbols to be used in the natural sciences and technology
• ISO 80000-4 Mechanics
• ISO 80000-5 Thermodynamics
• ISO 80000-6 Electromagnetism
• ISO 80000-7 Light
• ISO 80000-8 Acoustics
• ISO 80000-9 Physical chemistry and molecular physics
• ISO 80000-10 Atomic and nuclear physics
• ISO 80000-11 Characteristic numbers
• ISO 80000-12 Solid state physics
• IEC 80000-13 Information science and technology
• IEC 80000-14 Telebiometrics related to human physiology

References

ISO standards by standard number List of ISO standards / ISO romanizations / IEC standards 1–9999 1 2 3 4 5 6 7 9 16 31 -0 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 128 216 217 226 228 233 259 269 302 306 428 518 519 639 -1 -2 -3 -5 -6 646 690 732 764 843 898 965 1000 1004 1007 1073-1 1413 1538 1745 1989 2014 2015 2022 2047 2108 2145 2146 2240 2281 2709 2711 2788 2852 3029 3103 3166 -1 -2 -3 3297 3307 3602 3864 3901 3977 4031 4157 4217 4909 5218 5428 5775 5776 5800 5964 6166 6344 6346 6385 6425 6429 6438 6523 6709 7001 7002 7098 7185 7200 7498 7736 7810 7811 7812 7813 7816 8000 8178 8217 8571 8583 8601 8632 8652 8691 8807 8820-5 8859 -1 -2 -3 -4 -5 -6 -7 -8 -8-I -9 -10 -11 -12 -13 -14 -15 -16 8879 9000/9001 9075 9126 9293 9241 9362 9407 9506 9529 9564 9594 9660 9897 9945 9984 9985 9995 10000–19999 10006 10116 10118-3 10160 10161 10165 10179 10206 10218 10303 -11 -21 -22 -28 -238 10383 10487 10585 10589 10646 10664 10746 10861 10957 10962 10967 11073 11170 11179 11404 11544 11783 11784 11785 11801 11898 11940 (-2) 11941 11941 (TR) 11992 12006 12182 12207 12234-2 13211 -1 -2 13216 13250 13399 13406-2 13407 13450 13485 13490 13567 13568 13584 13616 14000 14031 14224 14289 14396 14443 14496 -2 -3 -6 -10 -11 -12 -14 -17 -20 14644 -1 -2 -3 -4 -5 -6 -7 -8 -9 14649 14651 14698 -2 14750 14764 14882 14971 15022 15189 15288 15291 15292 15398 15408 15444 -3 15445 15438 15504 15511 15686 15693 15706 -2 15707 15897 15919 15924 15926 15926 WIP 15930 16023 16262 16612-2 16750 16949 (TS) 17024 17025 17203 17369 17799 18000 18004 18014 18245 18629 18916 19005 19011 19092 (-1 -2) 19114 19115 19125 19136 19439 19500 19501 19502 19503 19505 19506 19507 19508 19509 19510 19752 19757 19770 19775-1 19794-5 19831 20000+ 20000 20022 20121 21000 21047 21500 21827:2002 22000 23270 23271 23360 24517 24613 24617 24707 25178 25964 26000 26300 26324 27000 series 27000 27001:2005 27001:2013 27002 27003 27004 27005 27006 27007 27729 27799 28000 29110 29148 29199-2 29500 30170 31000 32000 38500 42010 80000 -1 -2 -3 -4 -5 -6 -7 -8 -9 -10 -11 -12 -13 -14 Categories ISO standards ISO 639 ISO 3166 ISO / IEC standards OSI protocols All articles with prefix "ISO"