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PART

UNITSUnits are labels that are used to distinguish one type ofmeasurable quantity from other types. Length, mass, andtime are distinctly different physical quantities, andtherefore have different unit names, such as meters,kilograms and seconds. We use several systems of units,including the metric SI) units, the English or UScustomary units), and a number of others, which are ofmainly historical interest.This part of the book contains the following:

1. International System of Units2. Metric Units of Measurement3 . U.S. Units of Measurement4. Tables of Equivalents

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UNITSInternational System of Units

Quantitylengthmasstime

3

Name Symbolmeter mkilogram kgsecond S

INTERNATIONAL SYSTEM OF UNITSThe International Systemof Units, abbreviated as SI, isthe modernized version of the metric system establishedby international agreement.

Quantity Namearea square metervolume cubic meterspeed, velocity meter per secondacceleration meter per second

wave number reciprocal metermass density kilogram per cubicsquared

meter

Symbolm2m3d Sm / S

m-kg/m3

elecrc current ~ mo;em erethermodynamic kelvintem eratureamount of a substance I,

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Quantity


Name Symbol

ontinued rom 2specific volume

plane anglesolid angle

current density

radian radsteradian sr

magnetic field

forcepressure, stress

concentration

newton Npascal Pa

luminancemass fraction

cubic meter perampere per squaremeterampere per meter4candela per squaremeterkilogram per

frequency hertz HZ

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ontinued romelectric charge,quantity ofelectricityelectric potentialdifferencecapacitanceelectric resistanceelectric conductancemagnetic fluxmagnetic fluxdensitvinductanceCelsius temperatureluminous fluxilluminanceactivity of aradionuclideabsorbed dose,specific energy,kermadose equivalentcatalytic activity

coulomb cfarad

siemens IweberTeslahenry H

degree Celsius OClrnlumen

becquerel

I Gysievert svkatal kat

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6 UNITSInternational System of Units

Quantity Name Symboldynamic viscosity pascal second P a . s

electric chargedensity

moment of force newton meter N m

coulomb per cubic c / m 3meter

v melectric field strength volt per meter

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UNITS 7International System of Units

electric flux densitypermittivitypermeabilitymolar energymolar entropy, molarheat capacity

ays>exposure x and

coulomb per C/m2square meterfarad per meter Flmhenry per meter Hlmjoule per mole Jlmoljoule per mole J/ mol. K)kelvinkilogramcoulomb per C k

grayier secondbsorbed dose yateradiant intensi watt er steradianradiance watt per square w/ m sr

~meter steradian

hourdayliter

5. Units Outside the SI that Are Accepted forUse with the SIName Symbol Value in SI units

hd

1h 60 min 3600 s1 d 24h 86400 s

L 1L 1dm3 10-3m3

minute min 1min=60s

be1 B IlB=lOdB

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8 UNITSInternational System of Units

ontinued rom 5degree angle) 0minute angle)

second angle)

electronvolt eVunified atomic Umass unitastronomical uaunitnautical mileknotare ahectare

Ingstromcurierad rad

remrem

1 x/180)rad1= 1/60)O

x 10800)rad

1 1160)x 648000)rad

1eV 1.60218x lO-J1u 1.66054x kg1ua 1.49598x 10m1 nautical mile =1852 m1 knot 1852/3600m sl a = lo om 21ha 100 a 1O m2lbar =102kPa =105Pa

01A 0.lnm 10-Om1Ci 3.7 x loloBq1rad=1OP2GyIrem 10-2Sv

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UNITS 9Metric Units of Measurement

Name Symbol

millimeter mmcentimeter cm

6 SIPrefmesFactor Name Symb.

Value

1 mm=O.OOl m1 cm= 1Omm

hectokilo

Factor Name Symb.10 1 deci d

METRIC UNITS OF MEASUREMENTThe metric system was first proposed in 1791.TheFrench Revolutionary Assembly adopted it in 1795, andthe first metric standards a standard meter bar andkilogram bar) were adopted in 1799.