工程力学双语课件ch03-Equilibrium-of-Concurrent-Forces-in-a-Plane.pptVIP

Chapter3

EquilibriumofConcurrentForcesinaPlaneWangMing-lu

SpecializedVocabularyAction:作用(力),Reaction：反作用(力),反力,阻力Exert：施加〔力的作用〕Block：块Pole：杆Plate：板Beam：梁Shaft：轴Free-body：自由体Free-bodydiagram：受力图

ChapterObjectives.1.Drawacompleteandaccuratefree-bodydiagramshowingtheactingonapointinequilibrium.2.Explainthephysicalconditionsrequiredforequilibriumofapointanddemonstratehowtheseconditionsaredescribedmathematically.3.Applythegraphical,algebraic,andtrigonometricmethodsofearlierchaptertosolveforanyunknownforcesactingonapointinequilibrium.

3.1Conditionsforequilibrium.1.Aboutequilibrium.2.AboutConditionsforequilibrium.ABCDF1F2F3F4F4F3F2F1F1F1F2F2F2F3F3F3F4F4F4

3.2ActionandReactionNewton’sthirdlaw:actionandreaction

3.3Spacediagram,Free-bodydiagram.3.3.1Aboutspacediagram.3.3.2AboutFree-body.3.3.3AboutFree-bodydiagram.

3.4Constructionofafree-bodydiagram.3.4.1.Afree-bodydiagramshouldinclude:1.Anygivenanglesanddimensions2.Allforces,includingweights,andthosemagnitudeanddirectionsarespecifiedorimplied.3.Anyunknownanglesandforces.

3.4.2Example.Example3.1(P68).Example3.2(P71).Example3.3(P71).Example3.4(P72).Example3.5(P73).3.4Constructionofafree-bodydiagram.

3.4.3Problems.Dotheproblems3.1-3.8byyourself,andthenIwilltellyoutheanswersofthem.3.4Constructionofafree-bodydiagram.

3.5Threeconcurrentforcesinequilibrium.Twoconditionsforacompletedtriangle:1.Vectorsmustbeaddedinatail-totipfashion.2.Forequilibriumtoexist,theresultantmustequalzero.

3.5.2Example.Example3.6(P77).Example3.7(P80).Example3.8(P82).Example3.9(P84).3.5Threeconcurrentforcesinequilibrium.

3.6Fourormoreforcesinequilibrium.Studybyyourself.

3.7Equilibriumbyrectangularcomponentmethod.

3.7.2Example.Example3.11(P87).Example3.12(P90).Example3.13(P91).3.7Equilibriumbyrectangularcomponentmethod.

3.7.3P