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191 lines
5.9 KiB
Markdown
191 lines
5.9 KiB
Markdown
## Common Units & Unit Prefixes
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The following tables list all of the available unit prefixes, and many of the most
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commonly used units in simulations at the NASA, Johnson Space Center - Engineering Branch.
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Tables of units are provided for measuring [time](#time), [length](#length),
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[angle](#angle), [mass](#mass), [force](#force), [volt](#volt), [current](#current),
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[resistance](#resistance), [temperature](#temperature), [energy](#energy),
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[power](#power), [pressure](#pressure), [volume](#volume), and [frequency](#frequency).
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Each of the rows in each of the tables contain a list of identifiers that refer to a
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particular unit. Each of the identifiers in a list is synonymous. Also, characters
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between brackets are optional. For example, "s", "second", "seconds" are treated as
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being identical.
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It is **important** to note that these tables are not complete lists of all available units.
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If you're really curious, or if you just can't find the units you need, you could run
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`udunits2 -h` on the command line, follow the default database path listed at the bottom
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of the help text, and examine the (fairly easy to read) UDUNITS2 xml database files.
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You could also use `udunits2` with the `-H` option to determine whether the units you need exist, by guessing.
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<a id=unit-prefixes></a>
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### Unit Prefixes
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| Prefix | Value|
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|-------------------|------|
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| Y, yotta | 1e24 |
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| Z, zetta | 1e21 |
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| E, exa | 1e18 |
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| P, peta | 1e15 |
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| T, tera | 1e12 |
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| G, giga | 1e9 |
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| M, mega | 1e6 |
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| k, kilo | 1e3 |
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| h, hecto | 100 |
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| da, deka | 10 |
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| d, deci | 0.1 |
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| c, centi | 0.01 |
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| m, milli | 1e-3 |
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| μ, u, micro | 1e-6 |
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| n, nano | 1e-9 |
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| p, pico | 1e-12|
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| f, femto | 1e-15|
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| a, atto | 1e-18|
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| z, zepto | 1e-21|
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| y, yocto | 1e-24|
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<a id=common-predefined-units></a>
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###Common Predefined Units
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<a id=time></a>
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#### Time
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| Unit Identifier |
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|---------------------------------|
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| s, second[s] |
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| ms, millisecond[s] |
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| μs, microsecond[s] |
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| min, minute[s] |
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| h, hour[s] |
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| d, day[s] |
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<a id=length></a>
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#### Length
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| Unit Identifier |
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|---------------------------------|
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| m, meter[s] |
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| au, astronomical_unit[s] |
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| nmile, nautical_mile[s] |
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| ft, foot, feet |
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| in, inch[es] |
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| yd, yard[s] |
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| mi, mile[s] |
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| km, kilometer[s] |
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| cm, centimeter[s] |
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| mm, millimeter[s] |
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| um, μm, micrometer[s] |
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<a id=angle></a>
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### Angle
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| Unit Identifier |
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|---------------------------------|
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| rad, radian[s] |
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| °, degree[s] |
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| ′, arcminute[s] |
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| ″, arcsecond[s] |
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<a id=mass></a>
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### Mass
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| Unit Identifier |
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|---------------------------------|
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| kg, kilogram[s] |
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| g, gram[s] |
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| lb, pound[s] |
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| slug, slug[s] |
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NOTE: For Trick 13 and earlier, use 'sl' instead of 'slug'.
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<a id=force></a>
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### Force
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| Unit Identifier |
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|---------------------------------|
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| N, newton[s], kg.m/s^2, kg.m/s²|
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| lbf, pound[s]\_force |
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<a id=voltage></a>
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### Voltage
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| Unit Identifier |
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|---------------------------------|
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| V, volt[s] |
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| mV, millivolt[s] |
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| uV, μV, microvolt[s] |
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<a id=current></a>
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### Current
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| Unit Identifier |
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|---------------------------------|
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| A, amp, ampere |
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| mA, milliamp |
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| uA, μA, microamp |
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<a id=resistance></a>
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### Resistance
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| Unit Identifier |
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|---------------------------------|
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| Ω, ohm[s] |
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| kΩ, kohm[s], kiloohm[s] |
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| MΩ, Mohm[s], megaohm[s] |
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<a id=temperature></a>
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### Temperature
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| Unit Identifier |
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|---------------------------------|
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| K, °K, degK |
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| °C, degC |
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| °F, degF |
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| °R, degR |
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<a id=energy></a>
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### Energy
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| Unit Identifier |
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|---------------------------------|
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| J, joule[s] |
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| MJ, Mjoule[s], megajoule[s] |
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| W.h, watt.hour[s] |
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| kW.h, kilowatt.hour[s] |
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| BTU[s] |
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<a id=power></a>
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### Power
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| Unit Identifier |
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|---------------------------------|
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| W, watt |
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| kW, kilowatt |
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| MW, megawatt |
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| hp, horsepower |
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<a id=pressure></a>
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### Pressure
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| Unit Identifier |
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|---------------------------------|
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| Pa, pascal[s] |
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| psi |
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| atm, atmosphere |
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| mmHg, millimeter[s]\_Hg |
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| inHg, inch[es]\_Hg |
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<a id=volume></a>
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### Volume
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| Unit Identifier |
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|---------------------------------|
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| l, liter |
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| cm³, cm^3, (cm)³
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| gallon |
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| oz |
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<a id=frequency></a>
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### Frequency
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| Unit Identifier |
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|---------------------------------|
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| Hz, hertz, 1/s |
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| kHz, kilohertz, kiloHz
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| MHz, megahertz, megaHz
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<a id=counting></a>
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### Counting
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| Unit Identifier |
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|---------------------------------|
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| 1 |
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| count[s] |
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| bit[s] |
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| byte[s] |
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