小班講義高一物理第11講牛頓運(yùn)動(dòng)定律的應(yīng)用4—綜合訓(xùn)練

1、龍 文 教 育精品小班課程輔導(dǎo)講義講義編號(hào) 2013秋季 輔導(dǎo)科目： 物理 年級(jí)： 高一課 題第11講：牛頓運(yùn)動(dòng)定律的應(yīng)用4綜合訓(xùn)練教學(xué)目標(biāo)教學(xué)重點(diǎn)、難點(diǎn)教學(xué)內(nèi)容訓(xùn)練指要本套試題訓(xùn)練和考查的重點(diǎn)是：進(jìn)一步理解和掌握牛頓運(yùn)動(dòng)定律.能熟練地運(yùn)用牛頓定律解題，并能解答較簡(jiǎn)單的連接體問(wèn)題.第13題和第15題為創(chuàng)新題.第13題有利于提高學(xué)生的思維判斷能力.第15題有利于提高學(xué)生的審題能力.一、選擇題（每小題5分，共40分）1.如圖1101所示，懸掛于小車?yán)锏男∏蚱x豎直方向角，則小車可能的運(yùn)動(dòng)情況是圖1101a.向右加速運(yùn)動(dòng) b.向右減速運(yùn)動(dòng)c.向左加速運(yùn)動(dòng)d.向左減速運(yùn)動(dòng)2.如圖1102所示為一光滑豎

2、直圓槽，ap、bp、cp為通過(guò)最低點(diǎn)p與水平面分別成30、45、60角的三個(gè)光滑斜面，與圓相交于a、b、c點(diǎn).若一物體由靜止分別從a、b、c滑至p點(diǎn)所需的時(shí)間為t1，t2，t3，則圖1102a.t1t2t3b.t1t2t3c.t1=t2=t3d.t1=t2t33.在升降機(jī)內(nèi)的地板上放一秤，一人讓在秤上，用w表示升降機(jī)勻速運(yùn)動(dòng)時(shí)秤的示數(shù)，w1和w2分別表示升降機(jī)以大小為a的加速度加速上升和減速下降時(shí)稱的示數(shù)，則a.w2ww1b.ww1 ww2c.ww1=w2d.ww1 ww24.如圖1103所示，在托盤測(cè)力計(jì)的托盤內(nèi)固定一個(gè)傾角為30的光滑斜面，現(xiàn)將一個(gè)重4 n的物體放在斜面上，讓它自由滑下，那

3、么測(cè)力計(jì)因4 n物體的存在，而增加的讀數(shù)是圖1103a.4 nb.2 nc.0 nd.3 n5.如圖1104所示水平面上，質(zhì)量為10 kg的物塊a拴在一個(gè)被水平拉伸的彈簧一端，彈簧的另一端固定在小車上，小車靜止不動(dòng)，彈簧對(duì)物塊的彈力大小為5 n時(shí)，物塊處于靜止?fàn)顟B(tài)，若小車以加速度a=1 m/s2沿水平地面向右加速運(yùn)動(dòng)時(shí) 圖1104a.物塊a相對(duì)小車仍靜止圖1105b.物塊a受到的摩擦力將減小c.物塊a受到的摩擦力大小不變d.物塊a受到的彈力將增大6.如圖1105所示，a和b的質(zhì)量分別是1 kg和2kg，彈簧和懸線的質(zhì)量不計(jì)，在a上面的懸線燒斷的瞬間a.a的加速度等于3gb.a的加速度等于gc.

4、b的加速度為零d.b的加速度為g7.（2001年上海高考試題）如圖1106一升降機(jī)在箱底裝有若干個(gè)彈簧，設(shè)在某次事故中，升降機(jī)吊索在空中斷裂，忽略摩擦力，則升降機(jī)在從彈簧下端觸地后直到最低點(diǎn)的一段運(yùn)動(dòng)過(guò)程中a.升降機(jī)的速度不斷減小b.升降機(jī)的加速度不斷變大c.先是彈力做的負(fù)功小于重力做的正功，然后是彈力做的負(fù)功大于重力做的正功d.到最低點(diǎn)時(shí)，升降機(jī)加速度的值一定大于重力加速度的值圖1106 圖11078.如圖1107所示，一根輕質(zhì)彈簧上端固定，下端掛一質(zhì)量為m0的平盤，盤中有一物體，質(zhì)量為m.當(dāng)盤靜止時(shí)，彈簧的長(zhǎng)度比其自然長(zhǎng)度伸長(zhǎng)了l.今向下拉盤使彈簧再伸長(zhǎng) l后停止，然后松手放開.設(shè)彈簧總處

5、在彈性限度以內(nèi)，則剛剛松開手時(shí)盤對(duì)物體的支持力等于a.（1）mgb.（1）（mm0）gc. mgd. （mm0）g二、填空題（每小題6分，共24分）9.汽車在水平公路上做直線運(yùn)動(dòng)，它的功率保持不變，當(dāng)汽車的速度為4 m/s時(shí)，加速度為0.4 m/s2，汽車所受阻力恒為車重的0.01倍，若取g=10 m/s2，汽車行駛的最大速度為_ m/s.10.已知質(zhì)量為m的木塊的大小為f的水平拉力作用下沿粗糙水平地面做勻加速直線運(yùn)動(dòng)，加速度為a，則木塊與地面之間的動(dòng)摩擦因數(shù)為_.若在木塊上再施加一個(gè)與水平拉力f在同一豎直平面內(nèi)的推力，而不改變木塊的加速度的大小和方向，則此推力與水平拉力f的夾角為_.11.總

6、質(zhì)量為m的熱氣球由于故障在空中以速度v0勻速下降.為了阻止繼續(xù)下降，在t=0時(shí)刻，從熱氣球中釋放了一個(gè)質(zhì)量為m的沙袋.不計(jì)空氣阻力，當(dāng)t=_時(shí)，熱氣球停止下降，這時(shí)沙袋的速度為_.12.一輛小車在水平恒力f作用下，由靜止開始在水平面上勻加速運(yùn)動(dòng)t1 s后撤去f，小車再經(jīng)過(guò)t2 s停下.則小車加速階段的位移s1與減速階段的位移s2之比s1s2=_；小車牽引力f與所受的摩擦力ff之比f(wàn)ff=_.三、計(jì)算題（共36分）13.(12分)（2001年上海高考試題）如圖1108所示，一質(zhì)量為m的物體系于長(zhǎng)度分別為l1、l2的兩根細(xì)線上，l1的一端懸掛在天花板上，與豎直方向夾角為，l2水平拉直，物體處于平衡

7、狀態(tài).現(xiàn)將l2線剪斷，求剪斷瞬時(shí)物體的加速度.圖1108(1)下面是某同學(xué)對(duì)該題的一種解法：解：設(shè)l1線上拉力為t1，l2線上拉力為t2，重力為mg，物體在三力作用下保持平衡t1cos=mg，t1sin=t2，t2=mgtan剪斷線的瞬間，t2突然消失，物體即在t2反方向獲得加速度.因?yàn)閙gtan=ma，所以加速度a=gtan，方向與t2反方向.你認(rèn)為這個(gè)結(jié)果正確嗎?請(qǐng)對(duì)該解法作出評(píng)價(jià)并說(shuō)明理由. (2)若將圖1108中的細(xì)線l1改為長(zhǎng)度相同、質(zhì)量不計(jì)的輕彈簧，如圖1109所示，其他條件不變，求解的步驟和結(jié)果與(1)完全相同，即a=gtan，你認(rèn)為這個(gè)結(jié)果正確嗎?請(qǐng)說(shuō)明理由.圖110914.(

8、12分)一彈簧秤的秤盤質(zhì)量m=1.5 kg，盤內(nèi)放一物體p，物體p的質(zhì)量m=10.5 kg，彈簧質(zhì)量不計(jì)，其勁度系數(shù)為k=800n/m，系統(tǒng)處于靜止?fàn)顟B(tài)，如圖11010所示.現(xiàn)給p施加一個(gè)豎直向上的力f，使p從靜止開始向上做勻加速運(yùn)動(dòng)，已知在頭0.2 s內(nèi)f是變力，在0.2 s以后是恒力.求f的最小值和最大值各是多少?(g=10 m/s2)圖1101015.（12分）2001年9月11日，美國(guó)遭受了歷史上規(guī)模最大、損失最為慘重的恐怖主義襲擊，恐怖分子劫持客機(jī)分別撞擊了紐約的“世貿(mào)大樓”和華盛頓的“五角大樓”.其中一架客機(jī)攔腰撞到世貿(mào)大樓的南部塔樓第60層地方，并引起巨大爆炸，大約1 h后，南部

9、塔樓部分轟然倒塌（高約245 m），灰塵和殘骸四處飛濺，300多名救援警察和消防人員沒(méi)來(lái)得及逃生.我們不妨設(shè)置一個(gè)情境：當(dāng)處于倒塌部分正下方的地面人員，看到一塊質(zhì)量約為4 103 kg的樓墻塊豎直倒下的同時(shí)到作出反應(yīng)開始逃離需0.2 s的時(shí)間，逃離的安全區(qū)域?yàn)殡x大廈100 m外（實(shí)際的安全區(qū)要更遠(yuǎn)）.設(shè)該墜落塊與地面作用時(shí)間為0.05 s，不計(jì)空氣阻力，g取10 m/s2.求：（1）地面人員要逃離大廈到安全區(qū)至少要以多大速度奔跑？（忽略人的加速時(shí)間，百米短跑世界記錄為979）（2）該墜落塊對(duì)地產(chǎn)生的平均作用力多大？（3）由于爆炸引起地表震動(dòng)，設(shè)產(chǎn)生的縱波的傳播速率vp=9.1 km/s,橫波的

10、傳播速率vs=3.1 km/s，設(shè)在某處的地震勘測(cè)中心記錄到兩種不同震感之間的時(shí)間間隔t0=5 s,那么觀測(cè)記錄者與震源之間的距離s為多少千米？參考答案一、1.ad 2.c 3.bc 4.d 5.ac 6.ac 7.cd8.a 以盤和重物為一個(gè)整體加以隔離，平衡時(shí)kl=（m+m0）g，k=.用手向下拉，彈簧共伸長(zhǎng)l+l，彈力f=k（l+l）手的瞬時(shí)，根據(jù)牛頓第二定律f-（m+m0）g=（m+m0）.把f值代入得（l+l）-（m+m0）g=（m+m0）aa=g，方向向上.隔離盤中物體，設(shè)盤對(duì)物體的支持力為n，由牛頓第二定律n-mg=ma故n=mg+ma=mg+mg=（1+）mg，向上.二、9.2

11、010.= =arctan根據(jù)牛頓第二定律由f-mg=ma得=加力f后，水平加速度不變，有f+fcos-(mg+fsin)=ma與上式聯(lián)立得=arctan說(shuō)明推力方向只能與水平方向成角向下，因施推力后加速度不變，則必有fcos=fsin.即得tan=所以=arctan11.t=(m-m)v0/mg; 12.t1t2;fff=(t1+t2)t1三、13.因?yàn)閘2被剪斷瞬間，l1上的張力大小發(fā)生了變化.（1）錯(cuò).因?yàn)閘2被剪斷的瞬間，彈簧的長(zhǎng)度來(lái)不及發(fā)生變化，力t1的大小和方向都不能突變，（2）對(duì).14.依題意，0.2 s后p離開了托盤，0.2 s時(shí)托盤支持力恰為零，此時(shí)加速度為：a=（f大-mg

12、）/m(式中f大為f的最大值)此時(shí)m的加速度也為a.a=（kx-mg）/m所以kx=m（g+a）原來(lái)靜止時(shí)，壓縮量設(shè)為x0，則：kx0=（m+m）g而x0-x=at2/2由、有：at2即mg-ma=0.02aka=mg/（m+0.02k）=6 m/s2代入：fmax=m（a+g）=10.5（6+10）n=168 nf最大值為168 n.剛起動(dòng)時(shí)f為最小，對(duì)物體與秤盤這一整體應(yīng)用牛頓第二定律得f小+kx0-（m+m）g=（m+m）a代入有：fmin=（m+m）a=72 nf最小值為72 n.15.（1）墜落物做自由落體運(yùn)動(dòng)的時(shí)間：h=gt2落地速度v0=gt地面人員逃離時(shí)間t=t-0.2逃離速度

13、v=求得t=7 s v0=70 m/s v=10.3 m/s(2)根據(jù)牛頓運(yùn)動(dòng)定律可知：(f-mg)=ma=m求得f=5.64106 n(3)震動(dòng)同時(shí)產(chǎn)生傳播，則由勻速運(yùn)動(dòng)知求得s=23.1 km 第 11 次課后作業(yè)學(xué)生姓名： 1.在水平地面上運(yùn)動(dòng)的小車車廂底部有一質(zhì)量為m1的木塊，木塊和車廂通過(guò)一根輕質(zhì)彈簧相連接，彈簧的勁度系數(shù)為k.在車廂的頂部用一根細(xì)線懸掛一質(zhì)量為m2的小球某段時(shí)間內(nèi)發(fā)現(xiàn)細(xì)線與豎直方向的夾角為，在這段時(shí)間內(nèi)木塊與車廂保持相對(duì)靜止，如圖3310所示不計(jì)木塊與車廂底部的摩擦力，則在這段時(shí)間內(nèi)彈簧的形變?yōu)?) a伸長(zhǎng)量為 b壓縮量為c伸長(zhǎng)量為 d壓縮量為2. 如圖3311所示

14、，在光滑的水平面上，a、b兩物體的質(zhì)量ma2mb，a物體與輕質(zhì)彈簧相連，彈簧的另一端固定在豎直墻上，開始時(shí)，彈簧處于自由狀態(tài)，當(dāng)物體b沿水平向左運(yùn)動(dòng)，使彈簧壓縮到最短時(shí)，a、b兩物體間作用力為f，則彈簧給a物體的作用力的大小為()af b2f c3f d4f3如右圖所示，車廂里懸掛著兩個(gè)質(zhì)量不同的小球，上面的球比下面的球質(zhì)量大，當(dāng)車廂向右做勻加速運(yùn)動(dòng)時(shí)(空氣阻力不計(jì))，兩個(gè)小球穩(wěn)定后所處的位置下列各圖中正確的是()4.如圖3312所示，在光滑的水平面上放著緊靠在一起的a、b兩物體，b的質(zhì)量是a的2倍，b受到向右的恒力fb2 n，a受到的水平力fa(92t) n(t的單位是s)從t0開始計(jì)時(shí)，則

15、()aa物體在3 s末時(shí)刻的加速度是初始時(shí)刻的倍bt4 s后，b物體做勻加速直線運(yùn)動(dòng)ct4.5 s時(shí)，a物體的速度為零dt4.5 s后，a、b的加速度方向相反5. 如圖，風(fēng)洞實(shí)驗(yàn)室中可產(chǎn)生水平方向的、大小可調(diào)節(jié)的風(fēng)力?，F(xiàn)將一套有小球的細(xì)直桿放入風(fēng)洞實(shí)驗(yàn)室，小球孔徑略大于細(xì)桿直徑。（1）當(dāng)桿在水平方向上固定時(shí)，調(diào)節(jié)風(fēng)力的大小，使小球在桿上做勻速運(yùn)動(dòng)，這時(shí)小球所受的風(fēng)力為小球所受重力的0.5倍，求小球與桿間的滑動(dòng)摩擦因數(shù)。（2）保持小球所受風(fēng)力不變，使桿與水平方向間夾角為37，并固定，則小球從靜止出發(fā)在細(xì)桿上滑下距離s所需時(shí)間為多少？（sin37=0.6 cos37=0.8）winger tuiv

16、asa-sheck, who scored two tries in the kiwis 20-18 semi-final win over england, has been passed fit after a lower-leg injury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading into the encounter but austra

17、lia have not conceded a try since josh charnleys effort in their first pool match against england on the opening day.aussie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league international federation pl

18、ayer of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi - with a tournament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the all blacks in 2011.id give

19、 every award back in a heartbeat just to get across the line this weekend, said williams.the (lack of) air up there watch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier leagu

20、e match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he told bbc sport.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behavi

21、our of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has also ordered an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist in

22、sults from fans of cska. baumgartner the disappointing news: mission aborted.the supersonic descent could happen as early as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity a

23、nd limited cloud cover. the balloon, with capsule attached, will move through the lower level of the atmosphere (the troposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of com

24、mercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembl

25、ing an olympic diving platform.they blew it in 2008 when they got caught cold in the final and they will not make the same mistake against the kiwis in manchester.five years ago they cruised through to the final and so far history has repeated itself here - the last try they conceded was scored by e

26、nglands josh charnley in the opening game of the tournament.that could be classed as a weakness, a team under-cooked - but i have been impressed by the kangaroos focus in their games since then.they have been concentrating on the sort of stuff that wins you tough, even contests - strong defence, esp

27、ecially on their own goal-line, completing sets and a good kick-chase. theyve been great at all the unglamorous stuff that often goes unnoticed in the stands but not by your team-mates.it is as though their entire tournament has been preparation for the final.in johnathan thurston, cooper cronk, cam

28、eron smith and either billy slater or greg inglis at full-back they have a spine that is unmatched in rugby league. they have played in so many high-pressure games - a priceless asset going into saturday.the kiwis are a lot less experienced but winning a dramatic match like their semi-final against

29、england will do wonders for their confidence.they defeated australia in the four nations final in 2010 and the last world cup, and know they can rise to the big occasion.winger tuivasa-sheck, who scored two tries in the kiwis 20-18 semi-final win over england, has been passed fit after a lower-leg i

30、njury, while slater has been named at full-back but is still recovering from a knee injury aggravated against usa.both sides boast 100% records heading into the encounter but australia have not conceded a try since josh charnleys effort in their first pool match against england on the opening day.au

31、ssie winger jarryd hayne is the competitions top try scorer with nine, closely followed by tuivasa-sheck with eight.but it is recently named rugby league international federation player of the year sonny bill williams who has attracted the most interest in the tournament so far.the kiwi - with a tou

32、rnament high 17 offloads - has the chance of becoming the first player to win the world cup in both rugby league and rugby union after triumphing with the all blacks in 2011.id give every award back in a heartbeat just to get across the line this weekend, said williams.the (lack of) air up there wat

33、ch mcayman islands-based webb, the head of fifas anti-racism taskforce, is in london for the football associations 150th anniversary celebrations and will attend citys premier league match at chelsea on sunday.i am going to be at the match tomorrow and i have asked to meet yaya toure, he told bbc sp

34、ort.for me its about how he felt and i would like to speak to him first to find out what his experience was.uefa hasopened disciplinary proceedings against cskafor the racist behaviour of their fans duringcitys 2-1 win.michel platini, president of european footballs governing body, has also ordered

35、an immediate investigation into the referees actions.cska said they were surprised and disappointed by toures complaint. in a statement the russian side added: we found no racist insults from fans of cska. baumgartner the disappointing news: mission aborted.the supersonic descent could happen as ear

36、ly as sunda.the weather plays an important role in this mission. starting at the ground, conditions have to be very calm - winds less than 2 mph, with no precipitation or humidity and limited cloud cover. the balloon, with capsule attached, will move through the lower level of the atmosphere (the tr

37、oposphere) where our day-to-day weather lives. it will climb higher than the tip of mount everest (5.5 miles/8.85 kilometers), drifting even higher than the cruising altitude of commercial airliners (5.6 miles/9.17 kilometers) and into the stratosphere. as he crosses the boundary layer (called the tropopause),e can expect a lot of turbulence.the balloon will slowly drift to the edge of space at 120,000 feet ( then, i would assume, he will slowly step out onto something resembling an olympic diving platform.they blew it in 2008 when they got caught cold in the final and they will not make the