双语物理课件

高等教育出版社出版

Physicsdealswithmatter,motionandtheirinteraction.Physicsdealswithmatter1I'mWalterLewin.Iwillbeyourlecturerthisterm.Inphysics,weexploretheverysmalltotheverylarge.Theverysmallisasmallfractionofaprotonandtheverylargeistheuniverseitself.Theyspan45ordersofmagnitude-a1with45zeroes.***I'mWalterLewin.Iwillbeyou2MECHANICS（力学）:Kinematics（运动学）

Dynamics（动力学）MECHANICS（力学）:Kine3Chapter2&3MotioninOne,TwoandThreeDimensions（一维，二维和三维运动）2-1Descriptionofmotion

（运动描述）

Acoordinatesystem(坐标系)isbuiltonit.xyOzParticle(质点):

Relativityofdescriptionofmotion(运动描述的相对性)Absolutenessofmotion(运动的绝对性)ReferenceFrame(参照系)shouldbechosen.

anidealizedmodel(理想模型P12)Chapter2&32-1Descriptio42-2.

PositionandDisplacement(位置和位移）1.

PositionVector(位矢）Thepositionvectorextendsfromtheoriginofacoordinatesystemtotheparticle（从坐标原点到质点）.xyr(t)Inrectangularcoordinatesystem

(

直角坐标系)

:MotionFunction(

运动方程)：Itsthreecomponents(三个分量）arewrittenbythefollowingscalarfunctions（写为下列标量方程）TheTrajectoryequation

(

轨道方程)

canbeobtainedbyeliminatingtfromtheseequations（可从这些方程中消去t得出)ikjP,

z(t0)(t)zxyO2-2.PositionandDisplacemen52.

Displacement

(位移)——yx0r1(t)ABzr2(t+t

)r

Displacementdependsonlyonthepositionofinitialpointandfinalpoint,(i).

Themagnitudeofvector（矢量的量值）shouldbethelengthofthisvector（应为该矢量长度),i.e.(ii).

Differentfromthepath

(路程)Pathisthetotallengthofthetrajectorycurve.It’savector.

It’sascalar.independentwiththerealpath.2.Displacement(位移)——yx0r16InthelimitasΔt

0,（当Δt

0时极限下）r(t+Δt)r(t)

0ΔrΔr?Hey!xr(t+Δt)r(t)yz

P2P10ΔSInthelimitasΔt0,r(t+Δt)72-3.AverageVelocityandInstantaneousVelocity1.Averagevelocity(平均速度):2.Instantaneousvelocity(瞬时速度):Velocityisthe(first)derivativeofpositionvectorwithrespecttotime（速度是位矢对时间的一阶导数）.yx0r1(t)ABzr2(t+t

)r2-3.AverageVelocityandIns83.AverageandInstantaneousSpeedThemagnitudeofvelocityequalsspeed

(速度的量值等于速率):

AverageSpeed:（平均速率）InstantaneousSpeed:（瞬时速率）Note:Speed:,AverageSpeed:（平均速率）3.AverageandInstantaneousS92-4.AverageandInstantaneousAccelerationAverage

Acceleration:(平均加速度):Instantaneous

Acceleration:(瞬时加速度)

Δvv

(t)v

(t+Δt)xr(t+Δt)r(t)y

z

P2

P10v

(t)v

(t+Δt)··Accelerationisthetimederivativeofvelocity.Itisthesecondderivativeofpositionvectorwithrespecttotime2-4.AverageandInstantaneou10ThecomponentforminCartesiancoordinateis:（笛卡尔坐标分量式）

Directionof:Magnitudeof:ThecomponentforminCartesi11Example1:oxyPThemotionfunctionforaparticleisFind:

(1)itsrealdistanceduringt=0to2s(2)

Itsatt=2s

Example1:oxyPThemotionfunct12(2)(1)

RealDistance(路程）:—Itisaconstantandalong–ydirectionSolution:(2)(1)RealDistance(路程）:13例二质点以加速度a在x轴上运动,初速v0,处在x=x0位置.求任意时刻速度和位置。解：一维运动，去掉矢量符：两边积分得即例二质点以加速度a在x轴上运动,初速v014同理两边积分得即匀变速直线运动：有同理两边积分得即匀变速直线运动：有15Questions(思考题）P364;P6810Problems(练习题）P4046;P4167;P7258NextLecture:CurvilinearmotionQuestions(思考题）16高等教育出版社出版

Physicsdealswithmatter,motionandtheirinteraction.Physicsdealswithmatter17I'mWalterLewin.Iwillbeyourlecturerthisterm.Inphysics,weexploretheverysmalltotheverylarge.Theverysmallisasmallfractionofaprotonandtheverylargeistheuniverseitself.Theyspan45ordersofmagnitude-a1with45zeroes.***I'mWalterLewin.Iwillbeyou18MECHANICS（力学）:Kinematics（运动学）

Dynamics（动力学）MECHANICS（力学）:Kine19Chapter2&3MotioninOne,TwoandThreeDimensions（一维，二维和三维运动）2-1Descriptionofmotion

（运动描述）

Acoordinatesystem(坐标系)isbuiltonit.xyOzParticle(质点):

Relativityofdescriptionofmotion(运动描述的相对性)Absolutenessofmotion(运动的绝对性)ReferenceFrame(参照系)shouldbechosen.

anidealizedmodel(理想模型P12)Chapter2&32-1Descriptio202-2.

PositionandDisplacement(位置和位移）1.

PositionVector(位矢）Thepositionvectorextendsfromtheoriginofacoordinatesystemtotheparticle（从坐标原点到质点）.xyr(t)Inrectangularcoordinatesystem

(

直角坐标系)

:MotionFunction(

运动方程)：Itsthreecomponents(三个分量）arewrittenbythefollowingscalarfunctions（写为下列标量方程）TheTrajectoryequation

(

轨道方程)

canbeobtainedbyeliminatingtfromtheseequations（可从这些方程中消去t得出)ikjP,

z(t0)(t)zxyO2-2.PositionandDisplacemen212.

Displacement

(位移)——yx0r1(t)ABzr2(t+t

)r

Displacementdependsonlyonthepositionofinitialpointandfinalpoint,(i).

Themagnitudeofvector（矢量的量值）shouldbethelengthofthisvector（应为该矢量长度),i.e.(ii).

Differentfromthepath

(路程)Pathisthetotallengthofthetrajectorycurve.It’savector.

It’sascalar.independentwiththerealpath.2.Displacement(位移)——yx0r122InthelimitasΔt

0,（当Δt

0时极限下）r(t+Δt)r(t)

0ΔrΔr?Hey!xr(t+Δt)r(t)yz

P2P10ΔSInthelimitasΔt0,r(t+Δt)232-3.AverageVelocityandInstantaneousVelocity1.Averagevelocity(平均速度):2.Instantaneousvelocity(瞬时速度):Velocityisthe(first)derivativeofpositionvectorwithrespecttotime（速度是位矢对时间的一阶导数）.yx0r1(t)ABzr2(t+t

)r2-3.AverageVelocityandIns243.AverageandInstantaneousSpeedThemagnitudeofvelocityequalsspeed

(速度的量值等于速率):

AverageSpeed:（平均速率）InstantaneousSpeed:（瞬时速率）Note:Speed:,AverageSpeed:（平均速率）3.AverageandInstantaneousS252-4.AverageandInstantaneousAccelerationAverage

Acceleration:(平均加速度):Instantaneous

Acceleration:(瞬时加速度)

Δvv

(t)v

(t+Δt)xr(t+Δt)r(t)y

z

P2

P10v

(t)v

(t+Δt)··Accelerationisthetimederivativeofvelocity.Itisthesecondderivativeofpositionvectorwithrespecttotime2-4.AverageandInstantaneou26Thecomponentformin