一、參照物1、定義：為研究物體的運動假定不動的物體叫做參照物。2、任何物體都可做參照物3、選擇不同的參照物來觀察同一個物體結(jié)論可能不同。同一個物體是運動還是靜止取決于所選的參照物，這就是運動和靜止的相對性。二、機械運動1、定義：物理學(xué)里把物體位置變化叫做機械運動。2、特點：機械運動是宇宙中最普遍的現(xiàn)象。3、比較物體運動快慢的方法：⑴時間相同路程長則運動快⑵路程相同時間短則運動快⑶比較單位時間內(nèi)通過的路程。（根據(jù)運動路線）⑴曲線運動Ⅰ勻速直線運動：A、定義：快慢不變，沿著直線的運動叫勻速直線運動。定義：在勻速直線運動中，速度等于運動物體在單位時間內(nèi)通過的路程。物理意義：速度是表示物體運動快慢的物理量計算公式：B、速度單位：國際單位制中m/skm/hm/s單位大。換算：1m/s=3.6km/h。Ⅱ變速運動：定義：運動速度變化的運動叫變速運動。平均速度：=總路程總時間物理意義：表示變速運動的平均快慢五、力的作用效果1、力的概念：力是物體對物體的作用。2力的性質(zhì)：物體間力的作用是相互的（等，方向相反，作用在不同物體上。兩物體相互作用時，施力物體同時也是受力物體，反之，受力物體同時也是施力物體。3、力的作用效果：力可以改變物體的運動狀態(tài)。力可以改變物體的形狀。4、力的單位：國際單位制中力的單位是牛頓簡稱牛，用N力的感性認(rèn)識：拿兩個雞蛋所用的力大約1N。5、力的測量：⑴測力計：測量力的大小的工具。⑶彈簧測力計：

6、力的三要素：力的大小、方向、和作用點。7、力的表示法六、慣性和慣性定律：1、牛頓第一定律：態(tài)或勻速直線運動狀態(tài)。2、慣性：⑴定義：物體保持運動狀態(tài)不變的性質(zhì)叫慣性。⑵說明：慣性是物體的一種屬性。一切物體在任何情況下都有慣性。七、二力平衡：1、定義：物體在受到兩個力的作用時，如果能保持靜止?fàn)顟B(tài)或勻速直線運動狀態(tài)稱二力平衡。2、二力平衡條件：二力作用在同一物體上、大小相等、方向相反、兩個力在一條直線上3、力和運動狀態(tài)的關(guān)系：力不是產(chǎn)生（維持）運動的原因受非平衡力0力是改變物體運動狀態(tài)的原因一、功1、力學(xué)中的功距離，力學(xué)里就說這個力做了功。②力學(xué)里所說的功包括兩個必要因素：一是作用在物體上的力;二是物體在這個力的方向上移動的距離。2、功的計算：①物理學(xué)中把力與在力的方向上移動的距離的乘積叫做功。②公式：W=FS③功的單位：焦耳(J)，1J=1N·m。④注意：①分清哪個力對物體做功，計算時F就是這個力;②公式中S一定是在力的方向上通過的距離，強調(diào)對應(yīng)。③功的單位“焦”(?！っ?焦)，不要和力和力臂的乘積(牛·米，不能寫成“焦”)單位搞混。二、機械效率1、有用功和額外功①有用功定義：對人們有用的功，有用功是必須要做的功。例：提升重物W有用=Gh②額外功：額外功定義：并非我們需要但又不得不做的功例：用滑輪組提升重物W額=G動h(G動：表示動滑輪重)③總功：總功定義：有用功加額外功的和叫做總功。即動力所做的功。公式：W總=W有用+W額，W總=FS2、機械效率①定義：有用功跟總功的比值。②公式：η=W有用/W總③提高機械效率的方法：減小機械自重、減小機件間的摩擦。④說明：機械效率常用百分?jǐn)?shù)表示，機械效率總小于1①物理意義：功率是表示做功快慢的物理量。②定義：單位時間內(nèi)所做的功叫做功率③公式：P=W/t④單位：瓦特(W)、千瓦(kW)1W=1J/s1kW=103W四、動能和勢能1、動能①能量：物體能夠?qū)ν庾龉?但不一定做功)，表示這個物體具有能量，簡稱能。②動能：物體由于運動而具有的能叫做動能。③質(zhì)量相同的物體，運動的速度越大，它的動能越大;運動速度相同的物體，質(zhì)量越大，它的動能也越大。2、勢能①重力勢能：物體由于被舉高而具有的能量，叫做重力勢能。物體被舉得越高，質(zhì)量越大，具有的重力勢能也越大。②彈性勢能：物體由于彈性形變而具有的能量叫做彈性勢能。物體的彈性形變越大，具有的彈性勢能越大。③勢能：重力勢能和彈性勢能統(tǒng)稱為勢能。五、機械能及其轉(zhuǎn)化

1、機械能：動能與勢能統(tǒng)稱為機械能。如果只有動能和勢能相互轉(zhuǎn)化，機械能的總和不變，或者說，機械能是守恒的。2、動能和重力勢能間的轉(zhuǎn)化規(guī)律：;;3、動能與彈性勢能間的轉(zhuǎn)化規(guī)律：;為動能。一、 壓強1、壓力：①定義：垂直壓在物體表面上的力叫壓力。力，則壓力F=物體的重力G③研究影響壓力作用效果因素的實驗：課本甲、乙說明：受力面積相同時，壓力越大壓力作用效果越明顯。乙、丙說明壓力相同時、受力面積越小壓力作用效果越明顯。概括這兩次實驗結(jié)論是：壓力的作用效果與壓力和受力面積有關(guān)。3、壓強：①定義：物體單位面積上受到的壓力叫壓強。②物理意義：壓強是表示壓力作用效果的物理量③公式p=F/S(N)S2(m2)。Pa0.5Pa。者二、液體的壓強1、液體內(nèi)部產(chǎn)生壓強的原因：液體受重力且具有流動性2、液體壓強的規(guī)律：⑴液體內(nèi)部朝各個方向都有壓強;⑵在同一深度，各個方向的壓強都相等;⑶深度增大，液體的壓強增大;3⑴、公式適用的條件為：液體⑵、公式中物理量的單位為：p：Pa;g：N/kg;h：m驗充分說明這一點。4、連通器：⑴定義：上端開口，下部相連通的容器⑵原理：連通器里裝一種液體且液體不流動時，各容器的液面保持相平⑶應(yīng)用：茶壺、鍋爐水位計、乳牛自動喂水器、船閘等都是根據(jù)連通器的原理來工作的?！欣锊鹄麑嶒?。⑴實驗過程：在長約1m。⑵原理分析：在管內(nèi)，與管外液面相平的地方取一液片，因為液體不動故液片受到上下的壓強平衡。即向上的大氣壓=水銀柱產(chǎn)生的壓強。⑶結(jié)論：大氣壓p0=760mmHg=76cmHg=1.01×105Pa(其值隨著外界大氣壓的變化而變化)⑷說明：a;灌滿，則測量結(jié)果偏小。b本實驗若把水銀改成水，則需要玻璃管的長度為10.3mc將玻璃管稍上提或下壓，管內(nèi)外的高度差不變，將玻璃管傾斜，高度不變，長度變長。2——支持76cm1標(biāo)準(zhǔn)大氣壓10.3m3、大氣壓的變化2000米內(nèi)可近似地認(rèn)為高度每升高12米大氣壓約減小1,低空大氣壓減小得

快，高空減小得慢，且大氣壓的值與地點、天氣、季節(jié)、的變化有關(guān)。一般來說，晴天大氣壓比陰天高，冬天比夏天高。3、測量工具：⑴定義：測定大氣壓的儀器叫氣壓計。⑵分類：水銀氣壓計和無液氣壓計4、應(yīng)用：活塞式抽水機和離心水泵。四、流體壓強與流速的關(guān)系1、氣體壓強與流速的關(guān)系：在氣體和液體中，流速越大的位置壓強越小。2飛機的什力五1、浮力的大小。2、公式：F浮=G排=ρ液V排g六、浮力的應(yīng)用1、物體的浮沉條件：浸在液體中的物體，當(dāng)它所受的浮力大于重力時，物體上浮;當(dāng)它所受的浮力小于重力時，物體下沉;當(dāng)它所受的浮力等于重力時，懸浮在液體中，或漂浮在液面上。2、浮力的應(yīng)用輪船：采用空心的辦法增大排水量。氣球和飛艇：改變所受浮力的大小，實現(xiàn)上升下降。1.ReferenceDefinition:Anobjectthatisassumedtobeimmobileforstudyingthemotionofanobjectiscalledareferenceobject.AnyobjectcanbeusedasareferenceChoosedifferentreferenceobjectstoobservethesameobject.Theconclusionmaybedifferent.Whetherthesameobjectismovingorstationarydependsontheselectedreferenceobject,whichistherelativityofmovementandstillness.Second,mechanicalmovementDefinition:Inphysics,thechangeinthepositionofanobjectiscalledmechanicalmotion.Features:Mechanicalmovementisthemostcommonphenomenonintheuniverse.Themethodofcomparingthespeedoftheobject: ⑴thesametimeandthelongdistancewillmovefast ⑵thesamedistanceandtheshorttimewillmovefast⑶comparethedistancetraveledperunittime.Classification:(Accordingtothemovementroute) ⑴curvemovement⑵straightmovementⅠUniformlinearmotion:Definition:Thespeedisconstant,andthemotionalongastraightlineiscalledauniformlinearmotion.Definition:Inauniformlinearmotion,thespeedisequaltothedistancetraveledbyamovingobjectinunittime.Physicalmeaning:SpeedisaphysicalquantitythatindicateshowfastanobjectmovesCalculationformula:Speedunit:m/sintheinternationalunitsystem.Theunitofkm/hintransportislargerintheunitofm/s.Conversion:1m/s=3.6km/h.ⅡVariablespeedmovement:Definition:Themovementwhosemovementspeedchangesiscalledvariablespeedmovement.Averagespeed:=totaljourneytimePhysicalmeaning:Representstheaveragespeedofvariablespeedmovement

5.Theeffectofforce1.Theconceptofforce:Forceistheeffectofobjectsonobjects.2Thenatureoftheforce:Theforcesbetweentheobjectsaremutual(theinteractionforcesareequalinallcasesandinoppositedirections,actingondifferentobjects)Whenthetwoobjectsinteract,theforcingobjectisalsoaforcingobject.Conversely,theforcingobjectisalsoforcingobject.Theeffectofforce:Forcecanchangethemotionstateofanobject.Forcecanchangetheshapeofanobject.Unitofforce:TheunitofforceintheInternationalSystemofUnitsisNewtonforshort,whichisdenotedbyN.Perceptualunderstandingofforce:Theforceusedtotaketwoeggsisabout1N.Forcemeasurement:⑴Dynamometer:atooltomeasurethemagnitudeofforce.⑶Springdynamometer:Thethreeelementsofforce:thesize,direction,andpointofactionoftheforce.Representationofforce6.Inertiaandthelawofinertia:Newton'sfirstlaw:(1)ThecontentofNewton'sfirstlawis:Whenallobjectsarenotundertheactionofforce,theyalwaysmaintainastaticstateorastateoflinearmotionataconstantspeed.Inertia:(1)Definition:Thenatureofanobjectkeepingitsmotionstateunchangediscalledinertia.⑵Description:Inertiaisanattributeofanobject.Allobjectshaveinertiaunderanycircumstances.Seven,twoforcebalance:Definition:Whenanobjectissubjectedtotwoforces,ifitcanmaintainastaticstateorauniformlinearmotionstate,itiscalledatwo-forcebalance.Two-forcebalancecondition:thetwoforcesactonthesameobject,havethesamesize,oppositedirections,andthetwoforcesareonastraightlineTherelationshipbetweenforceandmotionstatus:ObjectstressconditionsObjectmotionstateDescriptionForceisnotthecauseof(sustained)movementUnbalancedforceHeliisnot0Forceisthereasonforchangingthemotionstateofobjects1.GongWorkinmechanics①Meaningofwork:Ifaforceactsonanobjectandtheobjectmovesacertaindistanceinthedirectionofthisforce,mechanicssaysthattheforcedoeswork.②Theworkmentionedinmechanicsincludestwonecessaryfactors:oneistheforceactingontheobject;thesecondisthedistancetheobjectmovesinthedirectionofthisforce.③Threecasesofnotdoingwork:powerfulwithoutdistance,distancewithoutpower,forceanddistancevertical.Calculationofwork:①Inphysics,theproductofforceandthedistancemovedinthedirectionofforceiscalledwork.②Formula:W=FS③Unitofwork:Joule(J),1J=1N·m.④Note:①Todistinguishwhichforcedoestheworkontheobject,Fistheforcewhencalculating;②Sintheformulamustbethedistancepassedinthedirectionoftheforce,andthecorrespondenceisemphasized.③Theunitofworkis"coke"(newton·meter=coke),don'tbeconfusedwiththeproductofforceandarm(newton·meter,can'tbewrittenas"focus").2.MechanicalefficiencyUsefulworkandextrawork①Definitionofusefulwork:Workthatisusefultopeople,usefulworkisworkthatmustbedone.Example:LiftingheavyobjectsWuseful=Gh②Extrawork:Definitionofextrawork:workthatisnotwhatweneedbuthavetodoExample:LiftingtheweightoftheweightwiththepulleysetW=Gmovingh(Gmoving:indicatestheweightofthemovingpulley)③Totalwork:

Definitionoftotalwork:Thesumofusefulworkplusextraworkiscalledtotalwork.Thatistheworkdonebypower.Formula:Wtotal=Wuseful+Wamount,Wtotal=FSMechanicalefficiency①Definition:theratioofusefulworktototalwork.②Formula:η=Wuseful/Wtotal③Methodtoimprovemechanicalefficiency:reducemechanicalweightandreducefrictionbetweenmachineparts.④Description:Themechanicalefficiencyisusuallyexpressedasapercentage,andthemechanicalefficiencyisalwayslessthan1①Physicalsignificance:Powerisaphysicalquantitythatindicatesthespeedofwork.②Definition:Theworkdoneperunittimeiscalledpower③Formula:P=W/t④Unit:Watt(W),kilowatt(kW)1W=1J/s1kW=103W4.KineticenergyandpotentialenergyKineticenergy①Energy:Anobjectcandoworkexternally(butnotnecessarily),whichmeansthattheobjecthasenergy,referredtoasenergy.②Kineticenergy:Theenergypossessedbyanobjectduetoitsmovementiscalledkineticenergy.③Forobjectswiththesamemass,thegreaterthespeedofmovement,thegreaterthekineticenergy;fortheobjectswiththesamespeed,thegreaterthemass,thegreaterthekineticenergy.Potentialenergy①Gravitypotentialenergy:Theenergythatanobjecthasduetobeingliftediscalledgravitypotentialenergy.Thehighertheobjectislifted,thegreaterthemassandthegreaterthegravitationalpotentialenergy.②Elasticpotentialenergy:Theenergypossessedbyanobjectduetoelasticdeformationiscalledelasticpotentialenergy.Thegreatertheelasticdeformationofanobject,thegreatertheelasticpotentialenergy.③Potentialenergy:Gravitypotentialenergyandelasticpotentialenergyarecollectivelycalledpotentialenergy.5.MechanicalenergyanditstransformationMechanicalenergy:Kineticenergyandpotentialenergyarecollectivelycalledmechanicalenergy.Ifonlykineticenergyandpotentialenergyaretransformedintoeachother,thesumofmechanicalenergyremainsunchanged,ormechanicalenergyisconserved.Theconversionlawbetweenkineticenergyandgravitationalpotentialenergy:①Forobjectswithacertainmass,iftheaccelerationdecreases,thekineticenergyincreases,thegravitationalpotentialenergydecreases,andthegravitationalpotentialenergyisconvertedintokineticenergy;②Forobjectswithacertainmass,ifthedecelerationrises,thekineticenergydecreases,thegravitationalpotentialenergyincreases,andthekineticenergyisconvertedtogravitationalpotentialenergyTheconversionlawbetweenkineticenergyandelasticpotentialenergy:①Ifthekineticenergyofoneobjectdecreasesandtheelasticpotentialenergyofanotherobjectincreases,thekineticenergyisconvertedintoelasticpotentialenergy;②Ifthekineticenergyofanobjectincreases,andtheelasticpotentialenergyofanotherobjectdecreases,theelasticpotentialenergyisconvertedintokineticenergy.1.Pressure1.Pressure:①Definition:Theforcepressedverticallyonthesurfaceofanobjectiscalledpressure.②Thepressureisnotallcausedbygravity.Whentheobjectisusuallyplacedonthetable,iftheobjectisnotsubjecttootherforces,thepressureF=thegravityoftheobjectG③Experimenttostudythefactorsthataffecttheeffectofpressure:TextbooksAandB:Whenthestressareaisthesame,thegreaterthepressure,themoreobvioustheeffectofpressure.BandCindicatethatwhenthepressureisthesame,thesmallerthebearingareais,themoreobviousthepressureeffectis.Summarizingtheconclusionsofthesetwoexperimentsisthattheeffectof

pressureisrelatedtopressureandforcearea.3.Pressure:①Definition:Thepressureontheunitareaofanobjectiscalledpressure.②Physicalsignificance:pressureisaphysicalquantitythatrepresentstheeffectofpressure③Formulap=F/STheunitofeachquantityis:p:Pascal(Pa);F:Newton(N)S:meter2(m2).④UnderstandingofthepressureunitPa:Thepressureonatablewhenanewspaperislyingdownisabout0.5Pa.Thepressureoftheadultwhenstandingonthegroundisabout:1.5×104Pa.⑤Methodtoincreaseordecreasepressure:changethepressure,changetheareaoftheforce,andchangethefirsttwoatthesametimeSecond,thepressureoftheliquidThereasonforthepressureinsidetheliquid:theliquidissubjecttogravityandhasfluidityThelawofliquidpressure:(1)Theliquidhaspressureinalldirections;⑵Atthesamedepth,thepressureinalldirectionsisequal;⑶Asthedepthincreases,thepressureoftheliquidincreases;⑷Thepressureoftheliquidisalsorelatedtothedensityoftheliquid.Atthesamedepth,thegreaterthedensityoftheliquid,thegreaterthepressure.3.Liquidpressureformula:p=ρgh(1)Theconditionsapplicabletotheformulaare:liquid⑵Theunitofphysicalquantityintheformulais:p:Pa;g:N/kg;h:m(3)Fromtheformula,itcanbeseenthatthepressureoftheliquidisonlyrelatedtothedensityoftheliquidandthedepthoftheliquid,buthasnothingtodowiththemass,volume,gravity,bottomareaofthecontainerandtheshapeofthecontainer.ThefamousPascal'sbrokenbarrelexperimentfullyillustratesthispoint.4.Connecter:(1)Definition:acontainerwithanopenupperendandaconnectedlowerpart⑵Principle:Whenaliquidisfilledinthecommunicatorandtheliquiddoesnotflow,theliquidlevelofeachcontainerremainslevel⑶Application:teapot,boilerwaterlevelgauge,automaticcowfeeder,shiplock,etc.allworkaccordingtotheprincipleoftheconnector.Determinationofatmosphericpressure-Torrysplitrateexperiment.⑴Experimentalprocess:Fillaglasstubewithalengthofabout1mwithaclosedendfilledwithmercury,blockthemouthofthetube,andtheninsertitbackwardsinthemercurytanktoreleasethefingersofthetubeopening.Atthistime,theheightdifferencebetweentheinsideandoutsideofthetubeisabout760mm.⑵Principleanalysis:Takealiquidtabletinthetube,whichislevelwiththeliquidsurfaceoutsidethetube.Becausetheliquidisnotmoving,theliquidtabletisbalancedbytheupperandlowerpressures.Thatis,theupwardatmosphericpressure=thepressuregeneratedbythemercurycolumn.⑶Conclusion:atmosphericpressurep0=760mmHg=76cmHg=1.01×105Pa(itsvaluechangeswiththechangeofexternalatmosphericpressure)⑷Description:aThepurposeoffillingthemercuryintheglasstubebeforetheexperimentis:aftertheglasstubeisinverted,thevacuumabovethemercuryis;ifitisnotfilled,themeasurementresultistoosmall.bInthisexperiment,ifmercuryischangedtowater,thelengthoftheglasstubeis10.3mcRaiseorlowertheglasstubeslightly,theheightdifferencebetweentheinsideandoutsideofthetubewillnotchange,tilttheglasstube,theheightwillnotchange,andthelengthwillbecomelonger.Standardatmosphericpressure-theatmosphericpressuresupporting76cmmercurycolumniscalledstandardatmosphericpressure.1Standardatmosphericpressure=760mmHg=76cmHg=1.013×105Pa,cansupportwatercolumnabout10.3mhighChangesinatmosphericpressureAtmosphericpressuredecreaseswithincreasingaltitude.Atanaltitudeof2000meters,itcanbeapproximatedthattheatmosphericpressuredecreasesbyabout1mmforevery12metersofaltitude.Thechangeofatmosphericpressurewithaltitudeisuneven.Thelow-levelatmosphe