Physics Notes O-levels - Syllabus [6091]

Chapter 1. Measurement Apparatus: Accuracy: Verniercalipers: 0.1mm/0.01cm Metrerule: 0.1cm/1mm Micrometerscrewgauge: 0.01mm Voltmeter/Ammeter: Halfsmallestdivision Chapter 2. Kinematics Displacement: Straight-linedistancefromoneobjecttoanother Distance: Howfarsomethingmoves(Notnecessarilystraight) Speed: Distance/Time Velocity: Displacement/Time Acceleration: Velocity/Time Graphsof motionof objects: Non-movingobject: Displacementremainsconstant,Velocityat0,Accelerationat0 Objectatuniformvelocityof1m/s: Displacementincreasesby1meverysecond,Velocityremainsconstantat1m/s,Accelerationat0 Objectatincreasingnon-uniformvelocity/acceleration: Displacementincreasesatincreasingrate,Velocityincreasesatincreasingrate,Accelerationincreasesatincreasingrate Objectatdecreasingnon-uniformvelocity/acceleration: Displacementincreasesatdecreasingrate,Velocityincreasesatdecreasingrate,Accelerationdecreasesatdecreasingrate Objectatuniformacceleration: Displacementincreases,Velocityincreasesatconstantrate,Accelerationconstant Objectatuniformdeceleration: Displacementincreases,Velocitydecreasesatconstantrate,Decelerationconstant Forvelocity/speed-timegraphs,displacement/distancetravelledistheareaunderthegraph. Airresistance:Whenanobject’sspeedincreases,airresistanceincreases.Whenairresistance=weightofobject,objectreachesTerminal Velocity,whereacceleration=0

Chapter 3. Forces Drawingofvectordiagrams:Nowayofdrawingitheresodoityourself Newton’s1stlaw:Objectsatrestormotionwillstayinthatwayuntilaresultantforceactsonit. Newton’s2ndlaw:Whenaresultantforceactsonanobjectofconstantmass,theobjectwillaccelerateinthedirectionoftheresultantforce.Theproductofthemassandaccelerationoftheobjectgivestheresultantforce.(F=m(kg)a) Newton’s3rdlaw:WhenonebodyexertsaforceABonanotherbody,thebodywillexertanequalandoppositeforceBAonthefirstbody.(Action-Reactionpairs) Chapter 4. Mass, Weight, Density Mass:Doesnotchangewithlocation.Measuredinkg. Weight:Changesbasedongravitationalforce.MeasuredinN.(Weightisaforce) Inertia:Thereluctanceofanobjecttochangeitsstateofrestormotionduetoitsmass.Thelargerthemassofanobject,theharderitisfortheobjecttostartmoving,slowdown,movefasterorstop. Density:Themassofanobjectperunitvolume.(Formula:Mass/Volume) Chapter 5. Turningeffect of Forces Momentofaforce:TheproductofaforceFandtheperpendiculardistancefromthepivottothelineofactionofforce.(FxD) PrincipleofMoments:Whenabodyisinequilibrium,thesumofclockwisemomentsaboutapivotisequaltothesumofanticlockwisemomentsaboutthesamepivot. CentreofGravity:Thepointonanobjectwhereallitsweightactson.Forobjectsofuniformdensity,thisisthegeometricalcentreoftheobject. Stability:Themeasureofanobject’sabilitytoreturntoitsoriginalpositionafteritisslightlydisplaced.

Typesof equilibrium: StableEquilibrium: UnstableEquilibrium: NeutralEquilibrium: Whentheobjectisslightlytilted,itscentreofgravityrisesbeforereturningtoitsoriginalheight.Asthelineofactionaboutitsweightstilllieswithinitsbase,themomentofitsweightaboutthepointofcontactcausestheconetoreturntoitsoriginalposition. Whentheobjectisslightlytilted,itscentreofgravitydropsandthelineofactionaboutitsweightliesoutsideitsbase.Themomentofitsweightaboutthecontactpointcausestheconetotopple. Whentheobjectisslightlytilted,itscentreofgravityremainsatthesameheight.Thelinesofactionthroughitsweightandthecontactpointcoincide,thusthemomentaboutitsweightabovethecontactpointis0,andtheobjectstaysinitsdisplacedposition, Chapter 6. Work, Energy, Power Energy:Thecapacitytodowork.MeasuredinJoules(J) Typesofenergy: Definition: Examples: Formula(ifany) Kineticenergy Energyofanobjectduetoitsmotion Wind,rollingball ½mv 2 (m=massinkg,v=speedofbody) Chemicalpotentialenergy Energystoredinabodyduetopositionofatomsorelectronsinthebody Food,batteries N.A.(notlearntyet) Elasticpotentialenergy Energystoredinabodyduetoelasticdeformation Spring,rubberband N.A.(notlearntyet) Gravitationalpotentialenergy Energystoredinabodyduetoitsheightfromtheground Bouncingballgoingupanddown,liftedobject mgh(m=massinkg,g=gravitationalforceinN,h=heightofobjectinm Electricalenergy Energyofanelectricchargeduetoitsmotionandposition Electricity Coveredinmoredetailinchapter17and19 Light Anelectromagneticwavevisibletotheeye Lightbulbs,LEDs N.A.(notlearntyet) Thermalenergy Energystoredinabodyduetoitstemperature Fire mc (m=massof△θsubstance,c=specificheatcapacityofsubstance, =△θchangeintemperature)

Nuclearenergy Energyreleasedduringanuclearreaction Nuclearpowerplants N.A.(notlearntyet) Principleofconservationofenergy:Energycannotbecreatedordestroyed,butcanbeconvertedfromonemoretoanother.Thetotalenergyinanisolatedsystemremainsconstant. Efficiency:Usefulenergyoutput/totalenergyinputx100% Workdone(inJ):Constantforce(inN)xdistancemovedbyobjectindirectionofforce(inm) Power(inW):Therateofworkdone(workdone/time) Chapter 7. Pressure Pressure:Themeasureofforceactingperunitarea.MeasuredinP(pascals)or force(inN)/area(inm 2 ) Waterpressure:Calculatedwithh 𝑷 g(h=heightinm, 𝑷 =densityinkg/m 3 ,g=gravitationalfieldstrengthinN/kg Pascal’sprinciple:Whenpressureisappliedtoanenclosedliquid,thepressureistransmittedequallytoallpartsoftheliquid. Chapter 8. Temperature Thermometricsubstance:Asubstancethatincreasesitsvolumedirectlyproportionaltothetemperature(e.g.mercury,alcohol) Icepoint:Usedasthelowerfixedpointofthethermometer.Itisthetemperatureofpuremeltingiceat1atmosphereanditsvalueis0 ℃ .Todeterminetheicepoint,placethebulbandlowerendofthethermometerintoafunnelcontainingpuremeltingice.Whenthelevelofthesubstanceremainsconstant,makeamarkingonthethermometer.Thisistheicepoint. Steampoint:Usedastheupperfixedpointofthethermometer.Itisthetemperatureofwaterboilingatoneatmosphereanditsvalueis100 ℃ .Todeterminethesteampoint,placethebulbofthethermometerjustaboveboilingwater.Whenthelevelofthesubstanceremainsconstant,makeamarkingonthethermometer.Thisisthesteampoint. Calculatingtemperaturewithathermometricsubstancethermometer/resistancethermometer:Usetheformula ,where istheunknowntemperatureθ = 𝑥θ − 𝑥0𝑥100 − 𝑥θ 𝑥100℃ θandxisthelength/resistanceofthesubstance/wireat0 ℃ , ,and100 ℃ .θ℃

Calculatingtemperaturewithathermocouple:Usetheformula ,where isthee.m.f.ϵ∝△θ ϵproducedinVand isthetemperaturedifferencebetweenthejunctionsin℃ .△θ Chapter 9. KineticModel of Matter Kineticmodelofmatter:Thekineticmodelofmatterstatesthatthetinyparticlesthatmakeupmatterarealwaysincontinuousrandommotion. Stateofmatter: Properties: Particlearrangement: Particlemovement: Solid Fixedshapeandvolume(Relatively)HighdensityIncompressible CloselypackedtogetherinaregularpatternoccupyingminimalspaceLargenumberofparticlesperunitvolume(Hencehighdensities) Particlesvibrateaboutfixedpositionsandtheyareheldinpositionbyverystrongattractiveforcesbetweenparticles(Hencetheyhavefixedvolumeandshape) Liquid Fixedvolumebutnofixedshape(Relatively)HighdensityIncompressible RandomlyarrangedwiththeparticlesslightlyfurtherapartthaninsolidsSlightlysmallernumberofparticlesperunitvolumecomparedtosolids(Hencerelativelyhighdensities) Particlesarefreetomoveaboutwithintheliquidbutthereareattractiveforcesbetweentheparticles(Hencetheyhavefixedvolumebutnofixedshape) Gas Nofixedshapeandvolume(Relatively)LowdensityCompressible RandomlyarrangedandfarapartfromoneanotherSmallnumberofparticlesperunitvolume(Hencelowdensities) Particleshaveverylittleattractiveforcesbetweenthemandmoveaboutrandomlyathighspeeds,occupyinganyavailablespace(Hencetheyhavenofixedshapeandvolumeandarecompressible) Brownianmotion:Therandommovementofparticlessuspendedinafluid.Whenthetemperatureincreases,theparticlesinthefluidmovefasterandmorevigorously. Pressureofagas:Becausetheairparticlesareincontinuousrandommotion,theycollideagainstthewallsofthecontainer.ByNewton’sThirdLaw,thiscreatesanequalbutoppositeforceonthemolecule.Asmanysuchcollisionsoccur,anaverageforceisexertedbythemoleculesonthewallsofacontainer,hencethereispressurefromthegas. Pressure-Temperaturerelationshipingases(Directlyproportional:p ∝ T):Asthetemperatureincreases,thepressureofthegasincreases.Whenthetemperaturerises,the