机电英语(英汉对照)力学里的基本概念

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1、Lesson4BasicConceptsinMechanicsSection1TextIntroductionInitsoriginalsense,mechanicsreferstothestudyofthebehaviorofsystemsunderactionofforces.Staticsdealswithcaseswheretheforceseitherproducenomotionorthemotionisnotofinterest.Dynamicsdealsproperlywithmotionsunderforces.Mechanicsissubdividedaccordingt

2、othetypesofsystemsandphenomenainvolved・AnimportantdistinctionisbasedonthesizeofthesystemThosesystemsarelargeenoughandcanbeadequatelydescribedbytheNewtonianlawofclassicalmechanics.Inthiscategory,forexample,arecelestialmechanicsthestudyofthemotionsofplanets,stars•andotherheavenlybodiesandfluidmechani

3、cswhichtreatsliquidsandgasesonamacroscopicscale・Fluidmechanicisapartofalargerfieldcalledcontinuummechanics,involvinganyessentiallycontinuousdistributionofmatterwhetherrigid,elastic,plastic,orfluid.Ontheotherhandzhebehaviorofmicroscopicsystemssuchasmolecules,atoms,andnucleicanbeinterpretedonlybythec

4、onceptsandmathematicalmethodsofquantummechanics

5、tes□Thesearenowknowntobeequivalent.Mechanicsmayalsobeclassifiedasnonrelativisticandrelativisticmechanics,thelatterapplyingtosystemswithmaterialvelocitiescomparabletothevelocityoflight.Thisdistinctionpertainstobothclassicalandquantummechanics.Finally,statisticalmechanicsusesthemethodsofstatisticsfor

6、bothclassicalandquantumsystemscontainingverylargenumberofsimilarsubsystemstoobtaintheirlarge-scaleproperties.BasicConceptsinMechanicsThatbranchofscientificanalysiswhichdealswithmotions,times,andforcesiscalledmechanicsandismadeupoftwoparts:staticsanddynamics.Staticsdealswiththeanslysisofstationarysy

7、stemse._thoseinwhichtimeisnotafactor,anddynamicsdealswithsystemswhichchangewithtime.Forcesaretransmittedintomachinemembersmatingsurfaces,e.g.,fromageartoashaftorfromonegearthroughmeshingteethtoanothergear,f