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CHAPTER1
Fundamentalsofvectorandtensor
calculus
1010Basicconcepts0Scalarsandvectors
Oneofthemethodsofclassificationofphysicalquantitiesis
basedonthedeterminationofquantitywithapre-determined
unitofmeasurement.Ifasinglenumberisenoughtodetermine
thespecificquantity,suchquantitiesarereferredtoasscalar
quantitiesandthenumbersdeterminingthemasscalars,asthey
correspondtopointsofaspecificscale.Thescalarsincludei.a.
temperature,density,energy,potential.Vectorlengthisalso
ascalar.Thesequantitiesarealsocalledinvariants,meaning
thattheyareunafectedbychangesoftheaxesofthecoordinate
system,e.g.byrotationofthesystem.
Otherquantities,e.g.velocity,acceleration,force,torque,cannot
beclearlydeterminedbytheirmeasure.Theirefectalsodepends
onthedirectionandthesense.Suchquantitiesarereferredto
asvectorquantities.Vectorquantitiescanberepresentedas
asegmentwithacertainlengthanddirection.
Vectorquantitiesrepresentingphysicalquantitiesshould,inad-
ditiontothethreecharacteristicsgiven(vectorlength,direction
andsense),haveaspecificpositioninagivenspace.Forthis
reason,wedividevectorsintothreegroups:
(a)freevectors,
(b)slidingvectors,
(c)boundvectors.
Freevectorsrepresentphysicalquantitieswithoutspecifying
theirpositioninspace.Thisisexemplifiedbythevectorsof
displacement,velocityandaccelerationofarigidbodyinits
translation.Allpointsoftherigidbodyhavethesamephysical
properties(thesamedisplacement,velocityandacceleration),
regardlessofthepointofapplication.
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