linear motion motion graphing simulation motivating the moving …phyz.org/phet/moving man.pdf ·...
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More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
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CONCEPTUAL PHYSICS: Hewitt/Baird Tech Lab
Linear Motion Motion Graphing Simulation
Motivating the Moving Man PurposeTostudyone‐dimensionalmotionthroughtheuseofacomputersimulationApparatuscomputerPhETsimulation:“MovingMan”(availableathttp://phet.colorado.edu)
Setup1.Turnthecomputeron,logonandallowittocompleteitsstartupcycle.
2.FindandstartthePhETSimulationsandruntheMovingMansimulation.Askyourinstructorforassistanceifneeded.
3.Locatethetime‐scaleexpansionbutton.Timeisthehorizontalaxis,nottheverticalaxis.Usethetimescaleexpansionbuttontoexpandthetimeaxissothatonly10secondscanbeseen.
4.Findandusethebuttonsthatwilldeletethevelocityvs.timeandaccelerationvs.timegraphs.Youareleftwithonegraph:positionvs.time.Anditshorizontalaxisnowrunsfromonly0to10seconds.
5.SetthecomputerasideandreadtheDiscussionsectionbelow.WhenyouhavefinishedreadingtheDiscussion,continuewiththeactivity.
DiscussionThesimulationprovidesuswithasimpleinterfacewecanusetostudymotiongraphs.Specifically,wecancontroltheposition,velocity,andaccelerationofanobjectandseethegraphsofposition,velocity,andaccelerationofthatobject.
Thesimulationallowsustomanuallycontroltheobjectbydraggingit.Wecanalsodragaposition“slider”control.
Moreimportantly,wecansetinitialconditionsfortheobjectthenletitsmotionproceed.Wecanpausethemotion,andthemotionislimitedinspacebythewalls.
ProcedureStep1:Completethematchingexerciseonthenextpage.Thenamesofmanyobjectsandbuttonsarelisted.Drawalineconnectingthenameofeachobjectorbuttontotheobjectorbutton,itself.YourscreenandFigure1shouldbeverysimilarinthatonlythepositionvs.timegraphisvisibleandthatthehorizontal(time)scalerunsfrom0to10seconds.PhETsimulationsarerevisedfromtimetotime,sosomeelementsofthescreenlayoutmayhavechanged.
Step2:ManualMana. Clickonthemananddraghiminthepositivedirection(towardthehouse)atasteadyrateof
1m/stothebestofyourability.Yourgraphwon’tbeperfect(limitationsofthecomputer’sinterfacepreventthis),buttrytomovethemanassmoothlyasyoucanat1m/s.
b. Whilethegraphisstillonthescreen,clicktheon‐screenbuttontoshowthevelocityvs.timegraph.Thisgraphplotsthevalueofthevelocityastimepasses.Clearthegraphsandtryagain.Movethemanmanuallyfrom0to10metersin10seconds—assmoothlyaspossible—at1m/s.Thesimulation’s“stopwatch”readingindicatestime.
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
c. Sketchtheresultingpositionvs.timeandvelocityvs.timegraphsonthegraphspageattheendofthiswrite‐up.
Step3:ProgrammedMana. Makesurethepositionandvelocitygraphsareshowing(withthetimescalesetfrom0to10
seconds)andtheaccelerationgraphishidden(deleted).Clearthegraphs.
b. Settheinitialpositionofthemanto0m.(Usethesliderortypeitintothevaluebox.)
c. Settheinitialvelocityofthemanto+1.0m/s.(Usethesliderortypeitintothevaluebox.)
d. Clickanon‐screenGobuttonandobservetheresultingmotiongraphs.Sketchbothgraphs(positionvs.timeandvelocityvs.time)onthegraphspageattheendofthelab.
e. Clearthegraphs.Settheinitialvelocityofthemanto+2.0m/sandrunthesimulationagain.Themotionendswhenthemanhitsthewall.Stopthesimulationwhenthatoccurs.Disregarddatafromthewallimpactandbeyond.Describetwodifferencesinthepositionvs.timegraph.(Hints:rise/run;duration.)
f. Addlinestoyourprevioussketchrepresentingthe+2.0m/smotion.Besuretolabelbothlinesnowplotted.Anddonotincludeplotteddataaftertheimpactwiththewall.
g. Addandlabeladashedlinetothegraphsshowingtheresultiftheinitialvelocityofthemanwere+5m/s.(Note:donotcarrythisprocedureoutonthesimulation.)
h. Describetwochangesthatoccuronthevelocityvs.timegrapheachtimeyoumaketheinitialspeedofthemangreater.
Step4:BackUptheChooChooa. Clearthegraphs.Theaccelerationgraphisstillhidden.
b. Settheinitialpositionofthemanto0m.Settheinitialvelocityofthemanto–2.0m/s.
c. Runthesimulationandobservethemotiongraphs.Again,themotionendswhenMovingMancrashesintothewall,sostopthesimulationwhenthathappens.SketchthegraphsonthesamesetofaxesusedforStep3,disregardingdatafromthewallimpactandbeyond.
d. Clearthegraphs.Settheinitialvelocityofthemanto–4.0m/sandrunthesimulation.Describetwodifferencesinthepositionvs.timegraph,andaddalinetoyourprevioussketchrepresentingthe–4.0m/smotion.Besuretolabelbothlinesnowplotted.
e. Addandlabeladashedlinetothegraphsshowingtheresultiftheinitialvelocityofthemanwere–10m/s.(Note:Donotcarrythisprocedureoutinthesimulation.)
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
f. Describetwochangesthatoccuronthevelocityvs.timegrapheachtimeyoumaketheinitialspeedofthemangreater(fasterinthenegativedirection).
g. Clicktheon‐screenbuttontoshowtheaccelerationvs.timegraph.Whatdoestheaccelerationvs.timegraphtellyouaboutthemotionsobservedsofar?
Step5:Pickin’UpthePace
a. Clearthegraphs.Allthreegraphsarenowshowing.
b. Settheinitialpositionofthemanto0m.Settheinitialvelocityofthemanto0m/s.Settheaccelerationofthemanto+0.5m/s2.
c. Runthesimulationandobservethemotiongraphs.Sketchthegraphsonthegraphpage.
d. Whatdoestheaccelerationvs.timegraphtellyouaboutthenatureofthismotion?(Donotrefertonumericalvaluesinyourresponse.)
Step6:OnceMore,WithFeelinga. Settheinitialpositionofthemanto0m.Settheinitialvelocityofthemanto0m/s.Setthe
accelerationtothemanto+2.0m/s2.
b. Runthesimulationandobservethepositionvs.timegraph.
i. Sketchthegraphonthesamesetofaxesaspart5.
ii. Howisthispositionvs.timegraphdifferentfromtheoneplottedinpart5above?
c.Howdoesthevelocityvs.timegraphdifferfromtheoneproducedinpart5above?
d.BasedonwhatyoulearnedinSteps5and6,sketchallthreemotiongraphsthatthemanwouldproduceifhestartedatx=0m,v=0m/s,anda=–1m/s2.Don’tactuallycarrythisprocedureoutonthesimulation.Simplysketchwhatyouthinkitshouldbebasedonyourexperience.
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
Step7:RoundTripa. Withallthreegraphsshowing,adjustthescaleofthetimeaxistodisplay20seconds.
b. Settheinitialpositionofthemanto–10m.Settheinitialvelocityto+3.0m/s.Settheaccelerationto–0.3m/s2.
c. Runthesimulationandobservethemotiongraphs.Sketchthegraphsonthegraphspage.
d. Selectthebestdescriptionsofthevelocityandaccelerationofthemanattheapexofhismotion(whenhe’sisfarthestfromhisstartingpoint).Chooseonedescriptionoftheman’svelocityandonedescriptionoftheman’sacceleration.Feelfreetousetherewindandforwardstepfeaturesofthesimulation.
__The velocity is positive: the man is moving to the right. __The velocity is zero: the man is at rest. __The velocity is negative: the man is moving to the left.
__The acceleration is positive: the man’s velocity is increasing. __The acceleration is zero: the man is maintaining constant velocity. __The acceleration is negative: the man’s velocity is decreasing.
e. Youoverhearaclassmatetellingsomeonethatit’spossibleforanobjecttobeatrestandacceleratingatthesametime.Whatdoyouthinkofthatstatement?
Step8:TheSloshingManPuzzlea. Clearallgraphs.Setthepositionnear–2m.Clickanddragthemanfrom–2mto+2mwith
uniformmotionandlethimrest.Thendraghimfrom+2mto–2mwithuniformmotionandlethimrest.Repeat.Theresultingpositionvs.timegraphshouldlooksimilartotheplotbelow.Don’tworryaboutthetimetoomuch;what’simportantismovingthemanoneway,thenresting,thenmovinghimtheotherway,thenresting.Yourlineswon’tbeasstraight,andthe“corners”ofyourgraphwillberounderthanthosedepictedbelow.
b. Examinethesectionoftheplotenclosedinthedashedbox.Thevelocityvs.timegraphhasapatternsimilartotheoneshownbelow.Unlikethetime‐alignedgraphsinthesimulation,thisgraphmayhavebeenshiftedhorizontally.Drawaboxtoenclosethesectionofthevelocitygraphthatcorrespondstotheboxedsectionofthepositionvs.timegraphabove.
Figure 2. Ideal Position vs. Time for Sloshing Man
Figure 3. Ideal Velocity vs. Time Segment for Sloshing Man
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
c. Theaccelerationvs.timegraphhasapatternsimilartotheoneshownbelow.Again,thisgraphmayhavebeenshiftedalongthetimeaxis.Anditisnotnecessarilytoscale.Drawaboxtoenclosethesectionoftheaccelerationgraphthatcorrespondstotheboxedsectionofthepositionvs.timegraphabove.
d. SketchthevelocityandaccelerationplotsinthespacebelowthepositionplotinFigure5below.
e. MatchthephrasesbelowtothemotionillustratedinFigure5.UsepointsA,B,C,orD,orsegments(e.g.,AB,BD).
Sustained positive velocity _______ Sustained negative velocity _______ Rest _______
Positive acceleration to start motion _______ Positive acceleration to stop motion _______
Negative acceleration to start motion _______ Negative acceleration to stop motion _______
Figure 4. Ideal Acceleration vs. Time Segment for Sloshing Man
Figure 5. Motion Graph Segment for Sloshing Man
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480
More curriculum can be found in Pearson Addison Wesley‘s Conceptual Physics Laboratory Manual: Activities · Experiments · Demonstrations · Tech Labs by Paul G. Hewitt and Dean Baird. ISBN: 0321732480