Mass of a substaplease 8nce is the measure of the quantity of matter contained in it. Mass per unit volume of a substance is referred to as its density. c) Write two other examples for derived units?
Answers
Explanation:
SI base units
The SI is founded on seven SI base units for seven base quantities assumed to be mutually independent, as given in Table 1.
Table 1. SI base unitsSI base unitBase quantityNameSymbollengthmetermmasskilogram kgtimesecondselectric currentampereAthermodynamic temperature kelvinKamount of substancemolemolluminous intensitycandelacd
For detailed information on the SI base units, see Definitions of the SI base units and their Historical context.
SI derived units
Other quantities, called derived quantities, are defined in terms of the seven base quantities via a system of quantity equations. The SI derived units for these derived quantities are obtained from these equations and the seven SI base units. Examples of such SI derived units are given in Table 2, where it should be noted that the symbol 1 for quantities of dimension 1 such as mass fraction is generally omitted.
Table 2. Examples of SI derived unitsSI derived unitDerived quantityNameSymbolareasquare meterm2volumecubic meterm3speed, velocitymeter per secondm/saccelerationmeter per second squared m/s2wave numberreciprocal meterm-1mass densitykilogram per cubic meterkg/m3specific volumecubic meter per kilogramm3/kgcurrent densityampere per square meterA/m2magnetic field strength ampere per meterA/mamount-of-substance concentrationmole per cubic metermol/m3luminancecandela per square metercd/m2mass fractionkilogram per kilogram, which may be represented by the number 1kg/kg = 1
For ease of understanding and convenience, 22 SI derived units have been given special names and symbols, as shown in Table 3.
Table 3. SI derived units with special names and symbolsSI derived unitDerived quantityNameSymbol Expression
in terms of
other SI unitsExpression
in terms of
SI base unitsplane angleradian (a)rad -m·m-1 = 1 (b)solid anglesteradian (a)sr (c) -m2·m-2 = 1 (b)frequencyhertzHz -s-1forcenewtonN -m·kg·s-2pressure, stresspascalPaN/m2m-1·kg·s-2energy, work, quantity of heat jouleJN·mm2·kg·s-2power, radiant fluxwattWJ/sm2·kg·s-3electric charge, quantity of electricitycoulombC -s·Aelectric potential difference,
electromotive forcevoltVW/Am2·kg·s-3·A-1capacitancefaradFC/Vm-2·kg-1·s4·A2electric resistanceohmV/Am2·kg·s-3·A-2electric conductancesiemensSA/Vm-2·kg-1·s3·A2magnetic fluxweberWbV·sm2·kg·s-2·A-1magnetic flux densityteslaTWb/m2kg·s-2·A-1inductancehenryHWb/Am2·kg·s-2·A-2Celsius temperaturedegree Celsius°C -Kluminous fluxlumenlmcd·sr (c)m2·m-2·cd = cdilluminanceluxlxlm/m2m2·m-4·cd = m-2·cdactivity (of a radionuclide)becquerelBq -s-1absorbed dose, specific energy (imparted), kermagrayGyJ/kgm2·s-2dose equivalent (d)sievertSvJ/kgm2·s-2catalytic activitykatalkats-1·mol