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11.1.1  Notation of unit objects

A unit object has two parts: a real number and a unit expression (a single unit or a multiplicative combination of units). The two parts are linked by the character _ ("underscore"). For example 2_m for 2 meters. For composite units, parenthesis must be used, e.g. 1_(m*s). See table 10.1 for a list of the basic units.


NameDescriptionNameDescription
_AAmpere_haHectare
_AngstromAngstrom_hpHorsepower
_BqBecquerel_inInch
_BtuBtu British thermal unit_inH20Inches of water, 60 degrees Fahrenheit
_CiCurie_inHgInches of mercury, 0 degree Celsius
_FFarad_jDay
_FdyFaraday_kWhKilowatt-hour
_GalGal (0.01 m/s2)_kgKilogram
_GyGray_kipKilopound-force
_HHenry_kmKilometre
_HzHertz_knotnautical miles per hour
_JJoule_kphKilometers per hour
_KKelvin_lLiter
_KcalKilocalorie_lamLambert
_MHzMegahertz_lbpound (1 pound = 16 oz)
_MWMegawatt_lbfPound-force
_MeVMegaelectronvolt_lbmolPound-mole
_NNewton_lbtTroy pound
_OhmOhm_lepLiter of oil equivalent
_PPoise (measures viscosity)_liqptUS liquid pint (1 US gallon = 8 US liquid pints)
_PaPascal_lmLumen
_RRoentgen_lxLux
_RankineDegree Rankine_lyrLight year
_SSiemens_mMetre (unit)
_StStokes_mhoMho
_SvSievert_miUSUS statute mile
_TTesla_mi^2Square international mile.
_VVolt_milMil
_WWatt_mileInternational mile
_WbWeber_milleNautical mile
_WhWatt-hour_mlmillilitre
_aAre (100 m2)_mmMillimetre
_acreAcre_mmHgMillimeter of mercury (torr), 0 degree Celsius
_arcminMinute of arc_mnMinute
_arcsSecond of arc_molMole
_atmAtmosphere_mphMiles per hour
_auAstronomical unit_ozOunce
_bBarn_ozUKUK fluid ounce
_barBar_ozflUS fluid ounce
_bblBarrel_oztTroy ounce
_bblepBarrel of oil equivalent_pcParsec
_buBushel (1 bushel=8 gallons UK)_pdlPoundal (force)
_buUSAmerican bushel_phPhot
_calCalorie_pkUS peck
_cdCandela_psiPounds per square inch
_chainChain (1 chain = 66 feet or 22 yards)_ptUKUK pint (1 UK gallon=8 UK pints)
_cmCentimetre_qtQuart
_ctCarat_radRadian
_cuUS cup_rdRad (1 rd=0.01 Gy)
_dDay_remRem
_dBDecibel_rodRod 1_rod=5.029215842_m
_degDegree (angle)_rpmRevolutions per minute
_degreeFDegree Fahrenheit_sSecond
_dynDyne_ssecond
_eVElectron volt_sbStilb
_ergErg_slugSlug
_fathFathom_srSteradian
_fbmBoard foot_stStere
_fcFootcandle (1 footcandle 10.764 lux)_tMetric ton
_fermiFermi_tbspTablespoon
_flamFootlambert_tecTonne of coal equivalent
_fmFathom_tepTonne of oil equivalent
_ftInternational foot_textex=10−6 (kg/m)
_ftUSSurvey foot_thermEEC therm
_gGram_tonShort ton (1 short ton = 2000 pounds)
_gaStandard freefall_tonUKLong (UK) ton
_galCCanadian gallon_torrTorr (mmHg)
_galUKUK gallon_trtour=2π rad
_galUSUS gallon_tspTeaspoon
_gfGram-force_uAtomic mass unit
_gmolGram-mole_ydInternational yard
_gonGrade_yrYear
_gradGrade_µMicron
_grainGrain (1 grain 0,0648 grams)µMicron
_hHour 
Table 11.1: Units

If a prefix is put before the unit then the unit is multiplied by a power of 10. For example, the prefix k or K, for kilo, indicates multiplication by 103. See table 11.2 for a list of the unit prefixes.


PrefixName(*10^) nPrefixName(*10^) n
Yyota24ddeci-1
Zzeta21ccent-2
Eexa18mmili-3
Ppeta15mumicro-6
Ttera12nnano-9
Ggiga9ppico-12
Mmega6ffemto-15
k or Kkilo3aatto-18
h or Hhecto2zzepto-21
Ddeca1yyocto-24
Table 11.2: Unit prefixes

You cannot use a prefix with a built-in unit if the result gives another built-in unit.
For example: 1_a is one are, but 1_Pa is one pascal and not 10^15_a.


Examples.


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