普通物理英语课件02_Kinematics.pdfVIP

One-DimensionalMotion:

Displacement,Velocity,Acceleration

Physics1425Lecture2

MichaelFowler,UVa.

Today’sTopics

•Thepreviouslecturecoveredmeasurement,

units,accuracy,significantfigures,estimation.

•Todaywe’llfocusonmotionalongastraight

line:distanceanddisplacement,averageand

instantaneousvelocityandacceleration,the

importanceofsign.

•We’lldiscusstheimportant

constant-accelerationformulas.

Kinematics:DescribingMotion

Kinematicsdescribesquantitatively

howabodymovesthroughspace.

We’llbeginbytreatingthebodyas

rigidandnon-rotating,sowecan

fullydescribethemotionby

followingitscenter.

Dynamicsaccountsfortheobserved

motionintermsofforces,etc.We’llgetto

thatlater.

MeasuringMotion:aFrameofReference

Frameofreference:Tomeasuremotion,wemust

firstmeasureposition.

z

(x,y,z)Wemeasurepositionrelativeto

somefixedpointO,called

ytheorigin.

O

Wegivetheball’slocationas

x(x,y,z):wereachitfromO

bymovingxmetersalongthe

Theframecanbeenvisionedas

threemetersticksatrightanglesx-axis,followedbyyparallel

toeachother,likethebeginningoftothey-axisandfinallyz

theframeofastructure.

paralleltothez-axis.

One-DimensionalMotion:DistanceTraveledand

Displacement

•Theframeofreference•Drivingacar,thedistance

inonedimensionisjusttravelediswhatthe