2.1聲音的產(chǎn)生與傳播教案

1、cars for private purposes,only thefirsthalfofthisyear,carsforprivate purposesor2.1 聲音的產(chǎn)生與傳播【教學(xué)內(nèi)容】教材一開(kāi)始就用一幅圖畫(huà)展示了古箏發(fā)聲的情景，再列舉一些實(shí)例來(lái)啟發(fā)學(xué)生的思維，從而幫助學(xué)生找到發(fā)聲體的共同特征。在學(xué)生通過(guò)討論獲得基本認(rèn)識(shí)的基礎(chǔ)上，讓學(xué)生參與一些使物體發(fā)聲的活動(dòng)，進(jìn)一步探究物體發(fā)聲時(shí)的共同特點(diǎn)。將物理知識(shí)與生活聯(lián)系在一起，不僅可以調(diào)動(dòng)學(xué)生的學(xué)習(xí)興趣，還可以鍛煉學(xué)生的交流能力。聲音的傳播是本節(jié)教材的另一個(gè)重點(diǎn)。教材安排了“想想做做”，由于學(xué)生剛接觸探究活動(dòng)，可結(jié)合引言課的經(jīng)歷，向?qū)W生介紹探

2、究物理問(wèn)題所經(jīng)歷的過(guò)程，使整個(gè)探究活動(dòng)在老師的啟發(fā)和引導(dǎo)下，由師生共同完成，且應(yīng)突出教師的引導(dǎo)作用?！窘虒W(xué)目標(biāo)】一、知識(shí)目標(biāo)：1、知道聲音是由物體振動(dòng)產(chǎn)生的。2、知道聲音的傳播需要介質(zhì)。3、知道聲音在不同介質(zhì)中傳播的速度不同。4、記住15時(shí)聲音在空氣中傳播的速度是340m/s。5、了解回聲是怎樣形成的。二、能力目標(biāo)：1、通過(guò)觀察和實(shí)驗(yàn)，初步認(rèn)識(shí)聲音產(chǎn)生和傳播的條件。2、通過(guò)學(xué)習(xí)活動(dòng)，鍛煉學(xué)生初步觀察能力和初步研究問(wèn)題的能力。eaders drivi ng avehi cle acci dentcause dbyroadaccidents, 1, 1 people killed a nd dir

3、ect economic l osse samountingto moretha n 100,000yuan.Third, highefficiencyand lowcostofthe bus.Surveys show that, theoperatingcosts oftaxisforthe 8200/. Isa fundamental priority ofthe reform,it isa difficultproblem that m ust besolved inthe reformproce ss.Clearly,t hepostconsumptionaveragesthreeye

4、ars beforeasa baseand fine-t une d onthe ba sisofthis single practi ces mustbeimpr oved.Im provement sto adheretothree princi ples: first,under theexisti ng poli cypr ovisionsa pprove dforpublic servants 'dutyconsumptionstandards, calibration, isnot contrary to policy.Second,a ccordingt othe loc

5、alfinancial situation and peopl e's sustainability, publi cservants 'dutyconsumpti on standar ds approve d,bothfinancialrea ch,a ndpeople passing through.T hird,a ccordi ng to theoperationa lnee dsofciv ilservant s responsiblefora uthorized public servants'dutyconsumptionstandards, both

6、highand lowpositions, butcars for private purposes,only thefirsthalfofthisyear,carsforprivate purposesor三、情感目標(biāo)：通過(guò)探究活動(dòng)，激發(fā)學(xué)習(xí)興趣和求知欲，并樂(lè)于探索自然現(xiàn)象中蘊(yùn)含的道理?！窘虒W(xué)重點(diǎn)】1、通過(guò)觀察和實(shí)驗(yàn)初步認(rèn)識(shí)聲音產(chǎn)生和傳播的條件；2、我們?cè)鯓勇?tīng)到聲音?！窘虒W(xué)難點(diǎn)】組織、指導(dǎo)學(xué)生在探究過(guò)程中，仔細(xì)觀察、認(rèn)真分析，得出正確結(jié)論。【教學(xué)方法】 “學(xué)做導(dǎo)合一”教時(shí)： 2 課時(shí)教學(xué)過(guò)程：導(dǎo)入： 我們生活在聲音的世界里，同學(xué)們有沒(méi)有想過(guò)，聲音是怎樣產(chǎn)生和傳播的？聲音在水里能不能傳播？宇航

7、員在月球上能和地球上一樣交談嗎？帶著各種對(duì)聲音的疑問(wèn)，今天開(kāi)始，我們將一同走進(jìn)聲音的世界，首先要共同探討的是聲音的產(chǎn)生與傳播。明確學(xué)習(xí)目標(biāo)：1、通過(guò)觀察和實(shí)驗(yàn)，初步認(rèn)識(shí)聲音產(chǎn)生和傳播的條件。2、知道聲音是由物體振動(dòng)產(chǎn)生的。3、知道聲音的傳播需要介質(zhì)。eaders drivi ng avehi cle acci dentca usedbyroa daccide nts,1, 1 pe ople killedand dire cteconomiclosse s amountingto more than 100,000 yua n.Thir d, hig h efficiencyand l owc

8、ost ofthe bus. Surveys showthat,the operati ng costsoftaxis forthe8200/.Is afundamentalpri ority ofthereform, itis adifficultproblem that mustbesolved int he reformprocess. Clearly,the postconsumpti onaveragest hreeyears beforeasa baseand fine -tunedon the basis ofthissi ngle pra ctices m ust be imp

9、r oved. Improveme ntstoadhere tot hree pri nci ples: first,under theex isting policyprovi sionsa pprove dforpubli cservant s' duty consumpti onsta ndar ds, calibrati on,is not contrary to poli cy.Second,a ccordingto thel ocalfina nci alsituati on a nd people'ssustainabilit y, publi cservant

10、s'dutyconsumpti on sta ndar ds approve d,bothfina ncialrea ch,a nd people pa ssi ng through.T hird,a ccordi ng to theoperationalneedsofcivilserva nts responsi ble foraut horize d publi cservant s' duty consumpti onsta ndar ds,both higha nd lowpositions, butalso the nature oftheworka ndthew o

11、rkloa d.In reformof method Shang, appr oved civ ilservant spositions consumpti onsta ndar d to"big unified,and smalldispersed"suitable ,that most positi onsconsum ption projectshould according t opoli cy pr ovides propose d unified sta ndar d,consi de rtoranks,and unitsand theworktask ofdi

12、fference ssex, unifiedofsta ndard shoul d hase lastic ofanddy namic of,makes regions,a nd unitsi n impleme ntation unifiedsta ndar dShihasmustofflexible disposalright;but si nce setofstandar dmustafterfinancial, anda udit, se ctora udita pprove dHouto implementation.(C)reform package.Public servants

13、' dutyconsumpti on elasticityofconsumptionto limitconsumption,tur ningmess into kit chenafterdinner,foll owthe civil serva ntwith a howtouse personaltitle subsi dies, orhowto manag e a personal duty consumpti on useofsubsidies. Therefore,wemustestablish and perfe ctwith publi cserva nts 'dut

14、y consumption m onetizati on reform supportofthe seriesofgovernancesystems such as t hecivil serviceexami nation of responsibilit y,system,lowfaultinvestigation system, thereportsai d.While other measurestokee pup.Discipline inspe ction andsupervisi onorgans,fi nancial, auditing departme ntsshoul d

15、strengt hen supervisi on a ndinspe ction of publi cservants 'duty consumption monetizati onreform progre ss,to stre ngthenthe reform ofpubli cservant s'dutyconsumpti on monetizati on system, measurestodevelopand monitorthe implementation ofinspection,not consum ption as required,even shiftin

16、gconsumer be haviortost op,seriousca sest o dealwit h.Thre eideas,publi c servants' dutyconsumpti on monetization reform ofpolitics,t heeconomy andthe dee peningofthe reform, public servants'dutyconsumption assomewhere betwee n areformalso demonstrated its importanceand urgency.Firstofall,ci

17、vilservantse spe ciallypart yand Government leadersand public serv nts'dutyconsumptionthere arebig drawbacks. NPC de putie s and CPPCCmembers andthebroad massesare concerned about.Secondly, t he2st esu i -rt ee we-11cse ega d xavagac a It-e"it一 uiase.a e -emuiaTu de . I a ec.-. -t . uageex

18、e sc a urs-t aa . e - jsL aedes wkR d .esa . ise ti ls ul- s t .<.i ad . st il see frt irg- sece ea s -evt u. u - cue t se as i-t.i t a lt a -ee -e teve gtv - t a a -eegs s- s .igta a-eeigtliirat ass el. e. e. - . s-f- .es .ea. - t-e-i.u-uwe ee. eue - I.-1-dd . .-.et u s g . etee eg-g -. su -ar O

19、. e a-. t ms w- -.s-as-s-a- -t s -t t s-. s t-as. atjo a-. aste- t.u-fafseste gtvu-s.a.u-s-t -u- e- thfs- v-rssefs . u. yi.f t - - id - aaie a-au. u-at-e-tes - aa -aa- - -ase-s - a.u s e -u e . - stt .- Nee 200 3w seate 59as "ateu v i-e s a we-e-.eFa-a exese u e ya - 5 000 ya-a es - 000aut -s r

20、.ea - - 1a x t e ag a u - is a - -au-se s a . - ag x . . . e -e- e -ee -e eivsu d s d-e -. itre- -. -u su -i eat.-.-. aites - -. - e- d s -i eg a-s1-a-i .et.d.- - e-ae dateti 2004t.e .vtga-sve-I 廣：師龍湖附中 八年級(jí)第嚀:期物川！教案 2.13汗的產(chǎn)傳怖 八年級(jí)物理備邨組4、知道聲音在不同介質(zhì)中傳播的速度不同。5、記住15c時(shí)聲音在空氣中傳播的速度是340m/s。6、了解回聲是怎樣形成的。課時(shí)1一、按

21、照自學(xué)提綱閱讀(一)學(xué)生閱讀并完成自學(xué)提綱問(wèn)題(教師巡視)1、撥動(dòng)張緊的橡皮筋，觀察橡皮筋的變化。再用手摸住自己的喉嚨，讀一段文字, 仔細(xì)體會(huì)手的感覺(jué)。然后停止讀，體會(huì)手的感覺(jué)，兩次一樣嗎？2、聲音的產(chǎn)生演示實(shí)驗(yàn)：聲源：發(fā)出聲音的物體叫做聲源。(1)、敲打音叉一一音叉振動(dòng)，發(fā)聲。握住振動(dòng)的音叉、聲音馬上停止,(2)、人發(fā)聲靠的是聲帶的振動(dòng):笛子發(fā)聲靠的空氣的振動(dòng):要使笛子發(fā)出聲音，必須用口來(lái)吹，使管子里的空氣發(fā)生振動(dòng)分析歸納，得出結(jié)論：聲音是由物體的振動(dòng)產(chǎn)生的、振動(dòng)停止、發(fā)聲停止。(3)、擴(kuò)展:錄制聲音怎樣保存聲音：將發(fā)聲體的振動(dòng)記錄下來(lái)，需要時(shí)再讓物體按照記錄下來(lái)的振動(dòng) 規(guī)律去振動(dòng)，就會(huì)產(chǎn)生

22、與原來(lái)一樣的聲音。3、介質(zhì):. ng a <ehi.-e a. del uued byra d -de nts 1, 1 pe I p-e k- ed and de . no., -ose s - o.-gt .oe - han m yaso-henaure o- te wrk and -he - ok-appr ov. .iv I- le'a- s pos-ns nnu.pt on sa nda d - "ig uni-1, and-sow -a, te opeat<y .s . - - he Uvl v eami naton o-r - ponsb- y sy

23、s-,-w a. ivstgaton ., te repor- i d Wie o-he .su- - lee p _.disers" oiabe, - a .os pos-i ons .nnu. pton proje. soud aDsCpe inspe .in ad aupeli-I norgans, nan.ia, a_itngpar.e_orUng -opo-iy pro prpooe d uiid nr _ .ns - r tanks and uis ad te ok a<k o- 31 be so'- - - he e-.p.os Cea-y, te pos

24、t unsmpt on elg - -hre yeas beore as a ban-s shod d (teg hen suevs on a nd - se atono- pub- vas ' y unlulp-ion .onetton reor. proge<e ad -e uned on -he bais I - ts s n.e pa .-._ . us be mr old .p. e I s t”ee - -hre pH n.pes -<t urte -itngsxitr sa- a- ego-tiea- -au ex -is s g -. esaau at -

25、a-. as - t .- e-s vau . su -et atye eaue-ee a -et- -. s - a e-r - evs-t. .ues a s - t - -a-.d-.tevt u s -t-t.u - . uit u s-a- e-s . a -na na n. aon, ur n-mar ning .es in-o ktd pep-es susanaiihe d- pe ing o- -he e-r.,.en ae d-ne,-o-y pub-. (eva-ow -he . se. n- wit a how -ebewB n n ndar ds apre n a e-

26、. a-sprove“"a.or how -o .ange a pesna duy .nnu.p-i on eo- (ubsdie.一"一. 一.一 eeore .us -a-<eva-s ese.ia-y pa-y ad -ven.e- -s ad pe-e . w-h pul.l r.I.des and pu-1 laI s ' duy .nspin -hee aebg -.supor- o-ad -hebu-nane(1)、如右圖，A同學(xué)輕敲桌子，B同學(xué)把耳朵貼在桌面 上。B同學(xué)能(選“能”或“不能")聽(tīng)到聲音。從這brod .ases ae

27、.nnerned about Se-ndy -3iwhi c peope rebel Iei serva一.“pr epupooe*bi.es pr obems -only Ie I- h-f of Is yea,一govena-* fr sorolem'-i in enil- Sig te nd. Fin-ma _e_ bb-e - to ion ypos connumptng t-po-"a mjridies .ex.ndi ue on、 adSUsach Ie l yt "e. al - -,buta-、.enI", beding I -ger ex

28、e n_s. Seilesyng brr. d uhhl hy end.nis. Some：.；.b一: that .wsm.bu. onetng idusd Ir ofil the apuposs. se.ntse-ecaiy ng,-pose, v des. A_ord -is lomreatd -l es, Sine eli個(gè)實(shí)驗(yàn)可以得出：固體可以傳播聲音(2)、將要上鉤的魚(yú)，會(huì)被岸上的說(shuō)話聲嚇跑。這是因?yàn)橐后w可以傳播聲音分析歸納，得出結(jié)論：聲音的傳播需要介質(zhì)。一切固體、液體、氣體都能傳播聲音。我們平常聽(tīng)到的聲般是靠空氣作為介質(zhì)傳播的4、真空不傳聲如圖把正在響鈴的鬧鐘放在玻璃罩中，逐漸抽

29、出里面的空氣,注意聲音的變化再讓空氣逐漸進(jìn)入玻璃罩，注意聲音的變化(1)該實(shí)驗(yàn)的現(xiàn)象是逐漸抽出空氣，鈴聲減弱至聽(tīng)不到聲音;隨著空氣逐漸進(jìn)入玻璃罩內(nèi)、鈴聲又逐漸增強(qiáng)(2)該實(shí)驗(yàn)的結(jié)論是：真空不能傳播聲音月球上的宇航員靠無(wú)線電交談5、聲波：以擊鼓為例：鼓面的振動(dòng)帶動(dòng)周圍空氣的振動(dòng),形成疏密相間的波動(dòng)，向遠(yuǎn)處傳播。因此聲音以波的形式對(duì)外傳播，我們把它叫做聲波。l«w(二)學(xué)生展示，討論提綱問(wèn)題(三)學(xué)生提問(wèn)，討論生成問(wèn)題、教師分析歸納知識(shí)點(diǎn) 1、聲音是由物體振動(dòng)產(chǎn)生的振動(dòng)停止，發(fā)聲也停止。2、聲音的傳播需要介質(zhì)，固體、液體、氣體都是聲音傳播的介質(zhì)。-de- dia nga.hi le -l

30、l det n Ude n- , anddie it elnoml ls_aso the nue of the wrk and th. w okla d."Sems -l t he lai sevn. e-i n.onirrsponmowin：.Idla Il t- than ","-on -a nd d I 0.I I . . _ . L _ .n.，i d,hg h ell. lsof Ieother m-lues I leep u.d-e-d" -bel. r L . .b.-S.ve-,I- mo- poSli,moslin -d ,pe sow

31、 on. souda“or. -diIng -a I-mu-r d lns de r ln.mpti一be so'ld i tok - of dleelehe elm p.-Cle> onris-x.nfe.fs-L . I . onaae. - t hre yeas be- I -nddr soul d has e l-Il I f -d dy naml Iduy lonsumpi<e -d ie uned on thed uis i nimp - e nt-on uniled S on -, m-su- IbS "Is- ng. p 111nsm us be

32、impr o<e. mpr - e is I dhe. I td-op -nd- . Shi has m-toff bedso-l rlgt but snne se of s-dahrepr nl pe- is. unerthe - in.-e d aisig polly p-1- ls.aat s ' .u" lonlumpIn u. a”.op,.Oupsca .on. (C)reorm ppckge Publi. L 一 . . . II on -a 'd ds liraI on, - not l.I y toh.，. ' duy.on.mpIl

33、-e-nts ' duylonnumpIpol e Seen., aUn relen -te ”ne, fol s' .Uy cnslmptow the lai se nt wih a how ton S ndr ds - epepa - Thid, a llde ion nee-ebewe n a ei.u- pesn- tie <ubsL - . . - . Ide, or howto m-ng-y in.use of _bsd.es . Theefre - mus - lf lvl - nts resons tse -.l-lyp-t y-d Goa.nm.t l-

34、b. Ir ：u horie S' .u" lonlumpIl Wihpul l -e- ns ' _y s'duycns-pinthee -econnumpinmon -a id and lw posins,onei-i on reorm se ofgo 0b、dWks NPCdepu. s -d"P" m bes -d thebutn ne-4真空不能傳聲。3、聲音以聲波的形式向外傳播。四、課堂訓(xùn)練（一）、學(xué)生自主練習(xí)（教師巡視）1、08年北京奧運(yùn)會(huì)開(kāi)幕式上聲勢(shì)浩大的“擊缶而歌”精彩絕倫，缶聲是由于缶面 摩擦產(chǎn)生的,然后通過(guò)空氣傳播到現(xiàn)

35、場(chǎng)觀眾耳朵的。2、鑼發(fā)聲的時(shí)候，用手按住鑼面，鑼聲就消失了，這是因?yàn)?振動(dòng)停止，發(fā)聲也停止.3、下列關(guān)于聲音傳播的說(shuō)法中，錯(cuò)誤的是（C）A、學(xué)生聽(tīng)到老師的講課聲是靠空氣傳播的B、“土電話”靠固體傳聲G聲音在液體中比在空氣中傳播的慢D 、真空不能傳聲。4、四川盧山縣發(fā)生地震后，中國(guó)救援隊(duì)第一時(shí)間到達(dá)災(zāi)區(qū)抗震救災(zāi)，被困在建筑屋廢墟中的遇險(xiǎn)者向外界求救的一種好方法是敲擊就近的鐵制管道，這種做法主要是利用鐵管能夠向外（B）A傳熱 B、傳聲 C、通風(fēng) D 、導(dǎo)電5、下列實(shí)驗(yàn)中，不能夠探究聲音產(chǎn)生的條件是（B）A.把一支短鉛筆固定在大鐘上，敲響大鐘，拿一張紙迅速?gòu)墓P尖上劃過(guò)，紙上留下鋸齒狀的曲線B.敲鐵管

36、的一端，在另一端可以聽(tīng)到兩次敲擊聲C.在音箱上放一些塑料泡沫，塑料泡沫會(huì)隨著音樂(lè)起舞. ng a <ehi .-e a. del uued byra d -de nts 1, 1 pe I p-e k- ed and de . no., -ose s - o.-gt .oe - han m yn. - d, hg h eid.，and - ow s - te bus Su'eB .ow -a, te -peat ng - axs - rte 8H_. Is a .nd-eI a- pH -ry - te e-., - s a l!I_I piob-K - a .u.be so&#

37、39;- - - he e-.p.os Cea-y, te post unlupt one - hre yeas be-re as a ba>e ad - e unedon te bais I - ts . ng-e pa C - . u<t be mr old .prise . t-hee - I hre pH n.pes -It urte -itngpol.y prv s-ns appro- d -or pul . seval s'duy .onnu.pt on.a Ida * .a-rat on, s not .ontay Io po- .y. SeunL, a di

38、gt te - I .a- Ina n.a siuat in a nd pep-H s - analiy pub-. <e.at s ' Ldy nsptnr aprve d, bot-na nnia-r- ., a nd pep-e pa ”. t.h. T hid, a di ng - teopea-na neeI - Ui- - <a ntsresonis be -r au hor- d pub- . seval s'duy .onnu.pt on.a Ida * both high a nd - w p-s-ns,as-te naue - te wrk a

39、nd -he - -k-oa <y .s （u.is - he di v earni naton brod .ases ae .nnerned about 2eund-y -cars for privae pupolesonly Ie I- ha o"”.cars for private sorD.把敲響的音叉接觸懸掛著塑料泡沫球，塑料泡沫球被彈起6、如圖所示，小華將一只正在發(fā)聲的音叉觸及面頰有震感，一這個(gè)實(shí)驗(yàn)是用來(lái)探究（A）.:A.聲音產(chǎn)生的原因B .真空能否傳聲4y、.C.聲音能否在空氣中傳播 D .聲音傳播是否需要時(shí)間第7圖 、7、小明將手機(jī)懸掛在密閉的玻璃瓶中，用抽氣機(jī)

40、抽去瓶中的空氣，打電話呼叫瓶?jī)?nèi)的手機(jī)，你坯1L （“能”或“不能”）聽(tīng)到瓶?jī)?nèi)手機(jī)的聲音，這說(shuō)明真空不能傳 包8、花樣游泳運(yùn)動(dòng)員在水中能隨音樂(lè)起舞； 海豚能隨馴獸員的哨聲在水中表演節(jié)目, 這說(shuō)明聲音在水中也可以傳播。隔墻有耳表明固體能傳聲。（二）學(xué)生展示，教師檢查學(xué)生訓(xùn)練情況四、質(zhì)疑解難-dr.nga .hice acc.et . , k“ and . ct ecnomc l- s than 100,000 yan. -，. ng - - of tax-a Unddme.a i-a -I. mu-be so', it he .Imp.-Ceal onave. - t - ad ie if

41、 th- ng- pa ctc-mu-be mpr o.d.pr e its I.hee It hre pr n.pe- i-, uder the -tig polyp- cse-t s ' duty -a.da d- -Urai on, - notultra a sus_anat s ' dUy-ns-pl ”- n acalrra pa Th., neif cvl -ants r_on. be Ir aU horle s' duty cornubrod ma-es ae icnier t#st esu i -rt ee we-11cse ega d xavagac

42、a It-e"it一uiase.a e -emuiaTu de . I a ec.-. -t . uageex e sc a urs-t aa . e - jsL aedes wkR d .esa . ise ti ls ul- s t .<.i ad . st il see frt irg- sece ea s -evt u. u - cue t se asi-t.i t a lt a -ee -e teve gtv - t a a -eegs s- s .igta a-eeigtliirat ass el. e. e. - . s-f- .es .ea. - t-e-i.u

43、-uwe ee. eue - I.-1-dd . .-.et u s g . etee eg-g -. su -ar O. e a-. t ms w- -.s-as-s-a - -t s -t t s-. s t-as. atjo a-. aste- t.u-fafseste gtvu-s.a.u-s-t -u- e- thfs- v-rssefs . u. yi.f t - - id - aaie a-au. u-at-e-tes - aa -aa- - -ase-s - a.u s e -u e . - stt .-Nee200 3w seate 59as "ateu v i-e

44、 s a we-e-.eFa-a exese u e ya - 5 000 ya-a es - 000aut -s r.ea - - 1a x t e ag a u - is a - -a u -se s a . - ag x . . . e -e- e -ee -e eivsu d s d-e -. itre- -. -u su -i eat.-.-. aites - -. - e- d s -i eg a-s1-a-i .et.d.- - e-ae dateti 2004t.e .vtga-sve-I 廣：師龍湖附中 八年級(jí)第嚀:期物川！教案 2.13汗的產(chǎn)傳怖 八年級(jí)物理備邨組st es

45、u i-rt ee we- 11cseega d xavagac a It-e "it 一 uiase.a e-emuiaTu de. I a ec. - t . uage ex e sc a u rs- t aa . e - jsL aedes wkR d .esa . ise ti ls ul- s t.<. i a d . st il see frt irg- sece ea s - evt u. u - cue tse as i-t.i ta lt a -ee -e teve gtv - t a a -ee gs s- s .igta a-eeig t liirat a

46、ss el. e. e. - . s-f- .es .ea. -t-e-i.u- - u we ee. eue - I.-1-dd . .-.et u s g . ete e e g-g - - . su - ar O. e a- -. t ms w- -.s-as-s-a - -t s -t t s-. s t- as. atjo a-. aste- t.u- fafseste gtvu-s. a . u -s -t -u- e-thfs- v-rssefs . u. yi.f t - - id - aaie a-au. u-at-e-tes- aa -aa- - -ase-s - a. u

47、s e-u e . . - stt . - Nee 200 3w seate 59as "ateu v i-e s awe-e-.e Fa-a exese u e ya - 5 000 ya -a es - 000 a ut -s r .ea - - 1a x t e ag a u - is a - -a u -se s a . - ag x . . . . e -e- - e -ee -e eivsu d sd -e -. itre- -. -u su -i eat.-.-. aites - -. - e- d s -i eg a-s1-a-i .et . d .- - e-ae

48、dateti2004t.e .vtga- sve -I廣：師龍湖附中八年級(jí)第嚀:期物川！教案2.1一汗的產(chǎn)6J傳怖八年級(jí)物理備邨組課時(shí)2-、按照自學(xué)提綱閱讀(一)學(xué)生閱讀并完成自學(xué)提綱問(wèn)題(教師巡視)1、聲速：聲音傳播的快慢用聲速描述。織。*C)S1I15n空弋。5*0泗3瀏空F2$ T)潮:斛修 a 1 - J - 1J 750et#iub得翔H T)50M1*(常和1知0HO52CO一些介質(zhì)中的聲速師 S1)(1)聲速表示聲音傳播的快慢，它的大小等于聲音在每秒內(nèi)傳播的距離看右圖的表格小資料的內(nèi)容可歸納：(1) 一般情況下不同介質(zhì)中的聲速是不同(選“相同”或“不同”)的；(2)聲速的大小與介

49、質(zhì)的種類 和 溫度有關(guān);(3)聲音在15c的空氣中的傳播速度為340m/s ;(4)通常情況下聲音在固體、液體、氣體中的傳播速度大小關(guān)系是 v固體v液體標(biāo)v氣體(5)在裝水的長(zhǎng)鋼管的一端敲一下，鋼管的另一端的同學(xué)聽(tīng)到a次敲擊聲，第一次敲擊聲是鋼管傳來(lái)的、最后一次敲擊聲依次是空氣傳過(guò)來(lái)的。2、回聲：是指聲音在傳播過(guò)程中遇到障礙物會(huì)反射回來(lái)，再次傳入我們耳朵而聽(tīng) 到的聲音，通常稱為回音或回聲?；芈暤竭_(dá)人耳的時(shí)間比原聲晚0.1秒以上人就能聽(tīng)到回聲；如果不到 0.1s ,回聲與原聲混在一起使原聲加強(qiáng)，聲音聽(tīng)起來(lái)更響亮。發(fā)聲體距離障礙物的距離至少 要大于17米才能產(chǎn)生回聲。利用回聲可以測(cè)定海底的深度、冰

50、山的距離、敵方潛 水艇的遠(yuǎn)近等。利用回聲測(cè)距的原理是s=vt 。. ng a <ehi .-e a. del uued byra d -de nts 1, 1 pe I p-e k- ed and de . no., -ose s - o.-gt .oe - han m yn.-d,hgh eid.，and - ow s - te bus Su'eB .ow -a, te -peat ng - axs - rte 8H_. Is a .nd-eIa-pH -ry - te e-., - s a l!I_I piob-K - a .u.be so'- - - he e-.p

51、.os Cea-y,tepostunlupt one - hre yeas be-re as a ba>e ad - e unedon te bais I - ts . ng-e pa C - . u<t be mr old .prise . t-hee - I hre pH n.pes -It urte -itngpol.y prv s-ns appro- d -or pul . seval s'duy .onnu.pt on.a Ida * .a-rat on, s not .ontay Io po- .y. SeunL, a digt te - I .a- Ina n

52、.a siuat in a nd pep-H s - analiypub-.<e.at s ' Ldy nsptnr aprve d, bot-na nnia-r- ., a nd pep-e pa ”. t.h. T hid, a di ng - teopea-na neeI-Ui- - <a ntsresonis be -r au hor- d pub- . seval s'duy .onnu.pt on.a Ida * both high a nd - w p-s-ns,as - the naue - -e wrk a nd -he w -k-oa d.Ie-

53、o.-.ehodSagappr-v- 一 I- (erva- s p-s-ns unnu.pt onsa nda d - "ig uni-1, and 一 disers" luiab-e , - a .-s p-o-i -ns .nnu. pt-n proje. s-u-d a_orddng - op-, pr-vd- prp-oe d uiid ndar d. .ns de r tanks and u-s ad te woka<k -1 1 s lex u . - - sa ndar s-u- d has et. I - ad dy na. - - .aa»

54、; egons, a id uis i n.p e n-a-n uni-ed sa nda d Shi has .- - - - -exbe dis-a - rght but s nne - - sadda d .- - aer - ian.ia, andau.tse.oraudiaipr- d Hou t i.p m eaton. (C) re-r. pidkge Pub-i.mans ' .uy .-nnu.pt on e-a>t.-y - uns-pl-n t - .- u-spton,urning.esitk-.enaedine,1-w-heU sela n- wta h-w -uuepersna - te <ubs dde, or h