The Free High School Science Texts: A Textbook for …

1 TheFreeHighSchool ScienceTexts:A TextbookforHighSchool Students 9, 20051 2003\FreeHighSchool ScienceTexts"Permissionis grantedtocopy, distributeand/ormodifythisdocument underthetermsof theGNUFreeDocumentationLicense, laterversionpublishedby theFreeSoftwareFoundation;withnoInvarian t Sections,noFront-Cover texts ,andnoBack-Cover copy of thelicenseis includedin thesectionentitled\GNUFreeDocumentationL icense".iContentsIPhysics11 .. `TODO'LIST.. Units(Syst emeInternationald'Unit es) .. Units.. Units.. Units.. to ChangeUnits|the\Multiplyby 1" Technique.. UnitsCanHelpYou.. a `sanity test'? .. cNotation,Signi cant FiguresandRounding..102 Waves andWavelike .. Waves : Amplitude.. Waves : Wavelength.. Waves : Period .. Waves : Frequency.. Waves : Speed.. Types of Waves.. Waves.

2 Waves : Re ection.. Waves : Refraction.. Waves : Interference.. Waves : StandingWaves.. Waves : Di raction.. Waves : Dispersion.. Waves:SoundWaves.. Cone.. EquationsandQuantities..353 .. andRealDepth:.. WhiteLight .. ection.. lenses.. Lenses.. cation.. ection.. usere ection.. ection.. re ection.. Mirrors(ConvergingMirrors).. Mirrors.. Refraction.. ection.. EquationsandQuantities..504 .. `TODO'LIST.. Vectors.. Vectors.. Vectors.. Vectors.. VectorAddition.. Vectors.. of Vectors.. onanincline.. reallyneedto learnaboutvectors?Aretheyreallyuseful?.. Important Quantities,EquationsandConcepts..835 `TODO'LIST.. a force?.. Forces.. 'sLawsof Motion.. ForcesStudiedLater.. Important Quantities,EquationsandConcepts.. 1026 rectilinearmotion?.. Motion.

3 EquationsandQuantities.. 1257 Momentum?.. a System.. Momentum.. momentumhave?.. Important Quantities,EquationsandConcepts.. 1398 .. of Energy.. Important Quantities,EquationsandConcepts.. 151 Essay1: Energy152 Essay2: Tiny, Violent Collisions158iv9 of Collisions.. :EnergyandHeat.. EquationsandQuantities.. 17510 .. problems.. EquationsandQuantities.. 18611 EquationsandQuantities.. 187 Essay3: PressureandForces18812 HeatandPropertiesof matter.. matter.. ,liquids,gasses.. uids.. phase.. solids.. ,stress.. state.. gasses.. a gas.. molecules.. cheatcapacity.. clatent heat.. of thermodynamics.. EquationsandQuantities.. 215v13 Electrostatics?.. 'sLaw .. eldmapslooklike?

4 TheElectricField?.. a Field.. erence.. 'sOil-dropExperiment .. EquationsandQuantities.. 23914 of Charge.. in a practicalcircuit.. current ow in a circuit.. voltage,current, andresistancerelate.. ,ammeters,andohmmeters.. 'sLaw.. in electriccircuits.. of voltagedrops.. "series"and"parallel"circuits?.. calculations.. Ohm'sLaw .. EquationsandQuantities.. 28515 .. measurement .. of AC magnitude.. 307vi16 andinductive circuits.. capacitor.. ltersandsignaltuning.. circuitelements,diode,LEDand elde ecttransistor,operationalampli .. a switch .. digitalelectronicslogicalgates,countingc ircuits.. 33317 theAtom.. theAtom.. guration.. of ionizationenergyto supportatomarrangement in PeriodicTable.

5 Ionisationenergiesto provideevidenceforarrangement of electronsintocoreandvalence.. Principle.. guration.. 34118 theideaof a quantum.. Waves:ElectromagneticWaves .. 34319 madeof .. radioactivity .. , , and rays .. theionizingradiation.. law .. dating.. screen.. 'schamber.. decay .. nature.. theuniverse.. 377A GNUFreeDocumentationLicense382viiiPartIP hysics1 Physicsis thestudyof a sensewe aremorequali edto dophysicsthanany we arebornwe studythethingsaroundus in ane orttounderstandhow theyworkandrelateto each to catch or throw a ballis eldof studywe refertoasphysicswe justtrytomake attemptto describe merelythelanguagewe to physicsis to relateeverythingyoulearnto thingsyouhave alreadynoticedin youreveryday at thingscloselyyoudiscover is thecontinuedscrutiny of everythingwe know abouttheworldaroundusthatleadspeopleto thelifelongstudyof simplequestionlike "Whyis theskyblue?

6 "which couldleadyouto electromagneticwaves which in turncouldleadyouwave particleduality andto energylevelsof atomsandbeforelongyouarestudyingquantumm echanicsor thestructureof thesectionsthatfollow noticethatwe willtryto describe how we willcommunicatethethingswe donewe canbegintheadventureof lookingmorecloselyat theworldwe live Explainwhatis meant by `physicalquantity'. Chapteris too fullof tablesandwords;need guresto make it moreinteresting. Make researchinghistoryof SI unitsa smallproject. Multiplyby onetechnique:notpositive!Suggestusingexp onents instead( pre xes).Thisalsoworksbetterforchangingcompl icatedunits(km=h 1tom:s ).Opinionthatthistechniqueis limitedin itsapplication. EditNASA story. TheTemperaturesectionshouldbe :I have editedtheoriginalsectionbutperhapsa moreaggressive editis justi edwiththedetailsde `TODO'LIST Writesectiononscienti cnotation,signi cant guresandrounding.

7 Addto sanity testtableof sensiblevaluesforthings. GraphCelsius/Kelvinladder. AddressPGCE comments make curtainsandneededto wouldneedto know how much materialwas wideand6 longwouldbe insu cient|youhave to specifytheunit( ).Withouttheunittheinformationis incompleteandtheshopassistant wouldhave to youweremakingcurtainsfora doll'shousethedimensionsmight be 2 centimetreswideand6 centimetreslong!3 BasequantityNameSymbollengthmetremmasski logramkgtimesecondselectriccurrentampere AthermodynamictemperaturekelvinKamount of :SI BaseUnitsIt is notjustlengthsthathave units,allphysicalquantitieshave units( ). unitsystemsin usetoday. Physicists,forexample,use4 mainsetsof units:SIunits, , theworldor whatareaof physicsyouworkin,theunitswillbe di erent. For example,in SouthAfricaroaddistancesaremeasuredin kilometres(SIunits),whilein Englandtheyaremeasuredin miles(imperialunits).

8 Youcouldeven make upyourownsystemof unitsif youwished,butyouwouldthenhave to teach peoplehow to useit! Units(Syst emeInternationald'Unit es)Thesearetheinternationallyagreeduponu nitsandtheoneswe was developedin Franceat thetimeof unitswhich canbe builtfromthe7 baseunitslistedin (incidentallythechoiceof theseseven was arbitrary).Theyarecalledbaseunitsbecause noneofthemcanbe expressedas combinationsof similarto breakinga languagedowninto a setof soundsfromwhich of viewingthebaseunitsis like madefromtheprimarycoloursbutnoprimarycol ourcanbe madeby combiningtheothertwo ( ).Thesymbols(orabbreviations)of unitsarealsowrittenwithlowercaseinitials exceptif theyarenamedafterscientists( (K) andtheampere(A)).To make lifeconvenient, particularcombinationsof workingwiththemeasier,butit is always correctto reduceeverythingto combinationsof SI concernedif theformulaelookunfamiliarat thisstage{we willdealwitheach in detailin thechaptersahead(aswellas many others)!}

9 It is veryimportant thatyouareableto say theunitscorrectly. For instance,thenewtonisanothernameforthekil ogrammetreper secondsquared(kg:m:s 2), whilethekilogrammetresquaredper secondsquared(kg:m2:s 2) is aspectof dealingwithunitsis thepre xesthattheysometimeshave(pre xesarewordsor letterswrittenin front thatchangethemeaning).Thekilogram(kg) is 1000gor 1 103g. Groupingthe103andthegtogetherwe canreplace4 QuantityFormulaUnitExpressedinNameofBase UnitsCombinationForcemakg:m:s 2N(newton)Frequency1Ts 1Hz(hertz)Work& EnergyF:skg:m2:s 2J(joule) :SomeExamplesof Combinationsof SI BaseUnitsAssignedSpecialNamesthe103witht hepre xk(kilo).Thereforethektakes theplaceof the103. Incidentallythekilogramis uniquein thatit is theonlySI baseunitcontaininga pre xTherearepre xesformany powersof 10( largesetof thesepre xes).

10 Thisis a largersetthanyouwillneedbutit serves as a good thepre xsymbolis letterfeaturestwicein thetable,it is writtenin uppercaseforexponents biggerthanoneandin lowercaseforexponents xeslistedin boldfaceshouldbe xSymbolExponentPre xSymbolExponentyottaY1024yoctoy10 24zettaZ1021zeptoz10 21exaE1018attoa10 18petaP1015femtof10 15teraT1012picop10 12gigaG109nanon10 9megaM106micro 10 6kilok103millim10 3hectoh102centic10 2decada101decid10 :UnitPre xesAsanotherexampleof theuseof pre xes,1 10 3gcanbe writtenas 1mg(1 milligram). UnitsTheremainingsetsof units,althoughnotusedby us,arealsointernationallyrecognisedandst illin useby willmentionthembrie replacedby thecentimetreandthekilogramis replacedby a simplechangebutit meansthatallunitsderivedfromthesetwo ,theunitsof forceandworkaredi (astheirnamesuggests)stemfromthedays whenmonarchs erent, exceptthemeasureof theunitsystemyouaremostlikelyto encounterif SI ,havingdi erent unitsin usefromplaceto placemakes scienti ccommunicationverydi themotivationforadoptinga setof themostsophisticatedchoiceof (such as thespeedof light)