Units Officially Accepted For Use With The SI
| Name | Symbol | Quantity | Equivalent SI unit |
|---|---|---|---|
| Widely used units expected to be used indefinitely | |||
| minute | min | time (SI unit multiple) | 1 min = 60 s |
| hour | h | time (SI unit multiple) | 1 h = 60 min = 3600 s |
| day | d | time (SI unit multiple) | 1 d = 24 h = 1440 min = 86400 s |
| degree | ° | plane angle (dimensionless unit) | 1° = (π / 180) rad |
| minute | ′ | plane angle (dimensionless unit) | 1′ = (1 / 60)° = (π / 10800) rad |
| second | ″ | plane angle (dimensionless unit) | 1″ = (1 / 60)′ = (1 / 3600)° = (π / 648000) rad |
| hectare | ha | area (decimal unit multiple) | 1 ha = 100 a = 10000 m2 = 1 hm2 |
| litre | l or L | volume (decimal unit multiple) | 1 L = 1 dm3 = 0.001 m3 = 1000 cc = 1000 cm3 |
| tonne | t | mass (decimal unit multiple) | 1 t = 103 kg = 1 Mg |
| Logarithmic units | |||
| neper | Np | dimensionless ratio of field quantities | LF = ln(F / F0) Np |
| dimensionless ratio of power quantities | LP = 1⁄2 ln(P / P0) Np | ||
| bel, decibel | B, dB | dimensionless ratio of field quantities | LF = 2 log10(F / F0) B |
| dimensionless ratio of power quantities | LP = log10(P / P0) B | ||
| Units with experimentally determined values | |||
| electronvolt | eV | energy | 1 eV = 1.60217653(14)×10−19 J |
| unified atomic mass unit dalton |
u Da |
mass | 1 u = 1 Da = 1.66053886(28)×10−27 kg |
| astronomical unit | ua | length | 1 ua = 1.49597870691(6)×1011 m |
| Natural units (n.u.) | |||
| n.u. of speed (speed of light in vacuum) | c0 | speed | 299,792,458 m / s (exact) |
| n.u. of action (reduced Planck constant) | ħ | action | 1.05457168(18)×10−34 J·s |
| n.u. of mass (electron mass) | me | mass | 9.1093826(16)×10−31 kg |
| n.u. of time | ħ / mec02 | time | 1.2880886677(86)×10−21 s |
| Atomic units (a.u.) | |||
| a.u. of charge (elementary charge) | e | electric charge | 1.60217653(14)×10−19 C |
| a.u. of mass (electron mass) | me | mass | 9.1093826(16)×10−31 kg |
| a.u. of action (reduced Planck constant) | ħ | action | 1.05457168(18)×10−34 J·s |
| a.u. of length, bohr (Bohr radius) | a0 | length | 0.5291772108(18)×10−10 m |
| a.u. of energy, hartree (Hartree energy) | Eh | energy | 4.35974417(75)×10−18 J |
| a.u. of time | ħ / Eh | time | 2.418884326505(16)×10−17 s |
Read more about this topic: Non-SI Units Mentioned In The SI
Famous quotes containing the words units, officially and/or accepted:
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—Willa Cather (1873–1947)
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—Barbara Ehrenreich (b. 1941)
“Masturbation is not only an expression of self-regard: it is also the natural emotional outlet of those who ... have already accepted as inevitable the wide gulf between their real futures and the expectations of their fantasies.”
—Quentin Crisp (b. 1908)