speed of sound - lazsta - home声音的速度lazsta回家

《speed of sound - lazsta - home声音的速度lazsta回家》由会员上传分享，免费在线阅读，更多相关内容在应用文档-天天文库。

1、SpeedofSoundThefollowingapparatuswasusedtocollectdatausedtocalculatethespeedofsoundinair.Describetheinvestigationcarriedoutusingthisequipment.Youmustusethewords:sensor,datalogger,reflection,echo,pulse.Underlinethesewordsinyourdescription.Thelengthofthepipewas2m(not1masshown

2、inthediagram)Thisgraphshowstheresultsobtainedbythedatalogger.Usethisdatatocalculatethespeedofsound.Analysis-solutionsDescriptionoftheinvestigation:Amicrophonesensorwasattachedtoadatalogger.Themicrophonewasplacedlevelwiththeopenendofa2mlengthof90mmdiameterPVCpipe.Theopposite

3、endofthepipewassealedwithaglassPetridishtapedintotheend.Thedataloggerwassetupusingthe“triggermode”sothatitwouldstartautomaticallywhenasoundwasdetectedandtocollectdatafor0.025seconds.Ashortsharpsound,apulse,wasproducedbyclappinghandsoncenearthemicrophone.Thesoundtravelledthr

4、oughtheairinthetubetotheglassbarrierattheotherend.Thesoundenergywasreflectedbacktothemicrophone,whichdetectedthisecho.Results-graphAnalysisWhenasoundwavepulseisreflectedfromasolidbarrierthereisaphasereversalofthepulse.Thisphenomenonisclearlyvisibleinthecaseofatransversepuls

5、einaspringasshowninthefollowingdiagram.Apulseapproachingabarrierattheright-handendonthelowersideofthespringisreflectedfromthebarriersothatitreturnsontheuppersideofthespring.Ifthegraphfromthedataloggerisexaminedcarefully,itcanbeseenthatdespiteitscomplexity,therearenegativepe

6、aksontheechocorrespondingtopositiveonesontheoriginalpulse–onesuchpairhasbeenidentifiedusingasquaresurroundingeachpointonthegraph.Thetimeintervalbetweentheseidentifiedpointsisthetimethatittakesthesoundpulsetotraveltotheendofthepipeandbackagain–fourmetres.Thetimeintervalisthu

7、scalculated:Dt=0.0129–0.0013=0.0116Thusthespeed,vofthesoundinairiscalculatedasfollows:v=r/Dt=4/0.0116=345ms–1DiscussionSoundvelocityinagasdependsonboththetypeofgasandthetemperatureofthegas.Inairthevelocityofsoundincreasesattherateof0.59ms-1°C-1fromthevalueofthespeedofsound,

8、331.45ms–1,atSTP(0ºCand1atmospherepressure).i.e.thespeedofsoundattemperatureTis:vT