理论力学第六章 英文ppt(推荐）.pptx

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Kinematics

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1Kinematics

Thescienceoftherelationbetweenagivenmotionofan

objectandtime.inwhichonlythegeometricalcharacteristicsofthemotionsuchastrajectories,velocitiesand

accelerations,arestudied,butnotthereasonsforthemotionconsidered.

2Objectsofkinematics

①Developsthemethodsfordescribingmechanicalmotions.

②Establishestherelationsbetweenthevariablesrelatedtomotion.

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3Whywestudyit?

Foundationsforthefollowingcoursesandanddirectapplicationsinengineeringpractice.

4Classificationofmotions

1)Motionofaparticles.

2)Motionofarigidbody.

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Chapter6:KinematicsofaParticle

§6.1Descriptionofthemotionofaparticleusingavectorofposition

§6.2Descriptionofthemotionofaparticleusingrectangularcoordinates

§6.3Descriptionofthemotionofaparticleusingnaturalcoordinates

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r=OM

2.Velocityofaparticle

1.Equationofmotion,trajectory(path)

3.Accelerationofaparticle

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1.Equationofmotion,trajectory

r=xi+yj+zk

2.Velocityofaparticle

∴V=vxi+vyj+v₂k

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Theequationofthetrajectory,

F(x,y,z)=0,canbedeterminedbyeliminatingtheparametert.

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Note:x,y,zarecontinuousfunctionsoftime

3.Accelerationofaparticle

Thepositionofamoving

particleisdeterminedby

measuringthedisplacement

alongitspathfroma

referencepoint.

1.Curvilinearcoordinate,naturalcoordinatesystem

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8

Inaddition,polarcoordinateandcolumncoordinatecanalsobeusedtodescribethemotionofaparticle.

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1)Equationofmotion:S=f(t)

r=f₁(t)

θ=f₂(t)

tangent

切线密切面Osculatingplane

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2)Naturalcoordinatesystem

副法线

Normalplane

法平面

PrincipalnormalM₁主法