H2 Physics Definitions

PhysicsDefinitions Topic Term Definition Measurements Systematicerror Systematicerrorscausemeasurementstobeconsistentlyhigher/lowerthanthetruevaluebyafixedextent. Accuracy Thedegreeofclosenessofameasuredvaluetothetruevalueofaquantity.Anexperimentthathassmallsystematicerrorsissaidtohavehighaccuracy. Randomerrors Randomerrorscausemeasurementstobescatteredaboutameanvalue. Precision Thedegreeofclosenessbetweenrepeatedmeasuredvalues.Anexperimentwithsmallrandomerrorsissaidtohavehighprecision. Kinematics Viscousdragforce Theforcewhichopposestherelativemotionofabodymovingthroughafluid. Distancevsdisp Distanceisthetotallengthoftheactualpathtravelled.Displacementisthestraightlinedistance. Forces Hooke’slaw Statesthatwithinthelimitofproportionality,theextensionproducedinamaterialisdirectlyproportionaltotheloadapplied.(F=kx) Pressure Isforceperunitarea,whereforceisactingperpendiculartoarea.(P=F/A) Density Ismassperunitvolumeofsubstance. Upthrust Isthenetupwardforceexertedbyafluidonabodyfullyorpartiallysubmergedinthefluid,duetoadifferenceinpressure. Principleofflotation Forabodyfloatinginafluid,theweightofthefluiddisplacedbythebodyisequaltotheweightofthebody. TorqueMOMENT Torque:turningeffectofacoupleMoment:Theproductofthemagnitudeoftheforceandtheperpendiculardistanceofthelineofactionoftheforcetothepivot.(M=Fd)

Couple Apairofforceswhichareequalinmagnitudebutoppositeindirection,andwhoselinesofactiondonotcoincide(parallel).Producerotationonly. Principleofmoments Forabodyinrotationalequilibrium,thesumofallclockwisemomentsaboutanypointisequaltothesumoftheanticlockwisemomentsaboutthatsamepoint. Rotationalequilibrium Thenetmomentonthebodyaboutanypointiszero. Translationalequilibrium Thenetforceonthebodyiszero. Dynamics centreofgravity pointatwhichthewholeweightofbodyappearstoact N1L Anobjectatrestwillremainatrest.Anobjectinmotionwillremaininmotionatconstantvelocityinastraightlineunlessacteduponbyaresultantexternalforce Inertia Reluctanceofastationarybodytostartmoving,orreluctanceofamovingbodytochangeitsmotion/Reluctanceofabodytochangeitsstateofmotion/Propertyofabodytostayinastateofrestorstayinmotionatconstantvelocityinastraightline.Massisameasureofinertiainabodytochangeinvelocity. N2L ● (MAG)rateofchangeoflinearmomentumofbodyisdirectlyproportionaltonetexternalforceexertedonit● (DIR)changeinmomentumandnetexternalforceareinthesamedirection VSstatetherelationbetweenforceandmomentum:forceisequaltotherateofchangeofmomentum.(SIunitscauseproportionalityconstanttobe=1.) N3L IfbodyAexertsaforceonbodyB,thenbodyBwillexertaforceequalandoppositeandofthesametypetobodyA. linearmomentum (p=mv)productofmassandvelocityAnditisinthedirectionofthevelocity

POCOM Totallinearmomentumofasystemofinteractingbodiesremainsconstantprovidedthereisnoresultantexternalforceactingonit. Impulse productofaverageforceexertedonbodyandtimeintervaloverwhichforceisapplied(Δ p=Ft) head-oncollision Velocitiesbeforeandafterthecollisionarealongthelinejoiningthe2centresofmass. perfectlyinelasticcollision collidingbodiescoalesce(sticktogether)andmoveoffwithcommonvelocityaftercollision. Inelasticcollision Referencetothespeedoftheobjects:Relativespeedofapproachoftheobjectsisgreaterthantherelativespeedofseparation.(cuzsomeKEislostaftercollision) WEP POCOE Energycannotbecreatednordestroyed,andcanonlybeconvertedfromoneformtoanother.Thetotalenergyofanisolatedsystemisconstant. Workdone Theproductofmagnitudeoftheconstantforceactingonthebodyandthedisplacementofthebodyinthedirectionoftheforce.(WD=Fd) Energy Isthestoredabilitytodowork. Potentialenergy Abilityofabodytodoworkduetoposition(gpe/electricpe)/shape(elasticpe) Power Therateofworkdone.(P=E/t) Efficiency Theratioofusefulpoweroutputtototalpowerinput. CM angularvelocity(ω)units:rads -1 productof2piandfrequencyofcircularmotion(ω=2π f)Rateofchangeofangulardisplacement period TimetakenforabodyinCMtomakeacompleterevolution

frequency Numberofrevolutionsperunittime Oscillations SHM (a=- ω 2 x)● accelerationisdirectlyproportionaltodisplacement● accelerationinoppositedirectiontodisplacement Angularfrequency(ω) (w=2 π f)productof2piandfrequencyofoscillation Displacement Shortestpossibledistanceinaspecifieddirectionfromequilibriumposition speed Distancetravelledbyawaveperunittimev=f(lambda) Frequency No.ofcompletewavesperunittime Wavelength Shortestdistancebetween2pointsonaprogressivewavewhichareoscillatinginphase period Timetakenfor1completeoscillationofaparticleonthewave amplitude Magnitudeofthemaximumdisplacementofaparticleonawave Wavefront Animaginarylinethatjoinsalladjacentpointsthathavethesamephaseofvibration damping progressivedecreaseinamplitudeofanoscillatorysystemcausedbydissipativeforces Explaindamping:decreaseinenergyofanoscillatingsystemovertime. resonance ● driverfrequency=naturalfrequencyofdrivensystem● oscillatorysystemrespondswithmaximumamplitudetoanexternalperiodicforce● thereismaximumenergytransfer refractiveindexofamedium theratioofspeedoflightinvacuumtothespeedoflightinthemedium Ultrasound Soundwithfrequency>20kHz

WaveMotion Progressivewave ● Energyistransferredinthedirectionofwavepropagation● Waveformappearstobemovingbutparticles(medium)donotgettransportedalongthewave Transversewaves Waveswheredirectionofoscillationisperpendiculartodirectionofenergytransfer(NOTwavepropagation). Longitudinalwaves Wavewheredirectionofoscillationisparallel(NOTsamedirection)todirectionofenergytransfer(NOTwavepropagation). compression/rarefaction regionwhereparticlesareclosest/furthestapart Phasedifference Phasedifferencebetween2particlesonawavemeasuresthefractionofacyclethat1particleismovingoutofstepwiththeotherparticle(units:radian) Polarisation Oscillationsareconfinedtoonedirectiononly……inaplanenormaltothedirectionofenergytransfer.- Oscillationsconfinedto1dir- Planenormal

- Dirofenergytransfer if2m:+onlytransversewavescanbepolarised Unpolarisedlightwave Oscillationsareinalldirections……inaplanenormaltothedirectionofenergytransfer. Intensity Powerperunitareatransferredacrossanareaperpendiculartothedirectionofenergytransfer.I=P/A Superposition Principleofsuperposition(interference) When2ormorewavesofthesametypemeetatapoint,theresultantdisplacement(NOTamplitude!)atthatpointisequaltothevectorsumofthedisplacementsduetotheindividualwavesatthatpoint. Stationarywaves Isformedwhentwoidenticalprogressivewavesofthesametype,amplitude,speedandfrequency(coherent)travellinginoppositedirectionssuperpose. Observableinterference 1. Coherence(samespeedandfrequency)2. Equalamplitudes(goodcontrast)3. Fortransversewaves,theymusteitherbeunpolarized,orpolarisedinthesameplane Diffraction spreading(NOTbending)ofwavesafterpassingthroughaslit(aperture)oraroundtheedgeofanobstacle Pathdifference Differenceindistancesfromthesourcesthatonewavetravelscomparedwithanotherwavetoreachaparticularpoint Coherence Constantphasedifferencebetweenwaves/sourcesofwaveswithtime Constructiveinterference ● occurswhen2waveshaveaphasedifferenceof0radandareinphase● componentwavessuperposetoformaresultantwithmaximumamplitudeandintensity Destructiveinterference ● Occurswhenthephasedifferenceis ,wavesareinantiphaseπ● Componentwavessuperpose,resultantisminimumamplitudeandintensity Resolvingpower )(𝑟𝑒𝑠𝑜𝑙𝑣𝑖𝑛𝑔 𝑝𝑜𝑤𝑒𝑟 = θ𝑚𝑖𝑛= λ𝑏 (minimumtheta)(Theangularseparationfromslittothe2sources)isequaltotheratioofwavelengthtotheslitwidth.

Rayleigh’scriterion Whentwoimagesarejustresolved,thecentralmaximumofthediffractionpatternofoneimagecoincideswiththefirstminimumofthediffractionpatternoftheotherimage. TemperatureandIdealGases Themole Onemoleofanysubstancecontains6.02x10^23particles. Idealgas AnidealgasobeystheequationofstatepV=nRT.Definethevariablesineqn:p=pressureofgas,v=volumeofgas,R=molargasconstant(NOT8.31),T=thermodynamictemperatureofthegas D.C.Circuits EMF Amountofnon-electricalenergyconvertedtoelectricalenergyperunitchargewhenthesourcedrivesachargearoundacompletecircuit. PD Amountofelectricalenergyconvertedtootherformsofenergyperunitchargewhenthechargepassesthroughanelectricalcomponent. Resistance TheratioofthepotentialdifferenceVacr