小班讲义高一物理第11讲牛顿运动定律的应用4—综合训练

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1、龙 文 教 育精品小班课程辅导讲义讲义编号 2013秋季 辅导科目： 物理 年级： 高一课 题第11讲：牛顿运动定律的应用4综合训练教学目标教学重点、难点教学内容训练指要本套试题训练和考查的重点是：进一步理解和掌握牛顿运动定律.能熟练地运用牛顿定律解题，并能解答较简单的连接体问题.第13题和第15题为创新题.第13题有利于提高学生的思维判断能力.第15题有利于提高学生的审题能力.一、选择题（每小题5分，共40分）1.如图1101所示，悬挂于小车里的小球偏离竖直方向角，则小车可能的运动情况是图1101A.向右加速运动 B.向右减速运动C.向左加速运动D.向左减速运动2.如图1102所示为一光滑竖

2、直圆槽，AP、BP、CP为通过最低点P与水平面分别成30、45、60角的三个光滑斜面，与圆相交于A、B、C点.若一物体由静止分别从A、B、C滑至P点所需的时间为t1，t2，t3，则图1102A.t1t2t3B.t1t2t3C.t1=t2=t3D.t1=t2t33.在升降机内的地板上放一秤，一人让在秤上，用W表示升降机匀速运动时秤的示数，W1和W2分别表示升降机以大小为a的加速度加速上升和减速下降时称的示数，则A.W2WW1B.WW1 WW2C.WW1=W2D.WW1 WW24.如图1103所示，在托盘测力计的托盘内固定一个倾角为30的光滑斜面，现将一个重4 N的物体放在斜面上，让它自由滑下，那

3、么测力计因4 N物体的存在，而增加的读数是图1103A.4 NB.2 NC.0 ND.3 N5.如图1104所示水平面上，质量为10 kg的物块A拴在一个被水平拉伸的弹簧一端，弹簧的另一端固定在小车上，小车静止不动，弹簧对物块的弹力大小为5 N时，物块处于静止状态，若小车以加速度a=1 m/s2沿水平地面向右加速运动时 图1104A.物块A相对小车仍静止图1105B.物块A受到的摩擦力将减小C.物块A受到的摩擦力大小不变D.物块A受到的弹力将增大6.如图1105所示，A和B的质量分别是1 kg和2kg，弹簧和悬线的质量不计，在A上面的悬线烧断的瞬间A.A的加速度等于3gB.A的加速度等于gC.

4、B的加速度为零D.B的加速度为g7.（2001年上海高考试题）如图1106一升降机在箱底装有若干个弹簧，设在某次事故中，升降机吊索在空中断裂，忽略摩擦力，则升降机在从弹簧下端触地后直到最低点的一段运动过程中A.升降机的速度不断减小B.升降机的加速度不断变大C.先是弹力做的负功小于重力做的正功，然后是弹力做的负功大于重力做的正功D.到最低点时，升降机加速度的值一定大于重力加速度的值图1106 图11078.如图1107所示，一根轻质弹簧上端固定，下端挂一质量为m0的平盘，盘中有一物体，质量为m.当盘静止时，弹簧的长度比其自然长度伸长了L.今向下拉盘使弹簧再伸长 L后停止，然后松手放开.设弹簧总处

5、在弹性限度以内，则刚刚松开手时盘对物体的支持力等于A.（1）mgB.（1）（mm0）gC. mgD. （mm0）g二、填空题（每小题6分，共24分）9.汽车在水平公路上做直线运动，它的功率保持不变，当汽车的速度为4 m/s时，加速度为0.4 m/s2，汽车所受阻力恒为车重的0.01倍，若取g=10 m/s2，汽车行驶的最大速度为_ m/s.10.已知质量为m的木块的大小为F的水平拉力作用下沿粗糙水平地面做匀加速直线运动，加速度为a，则木块与地面之间的动摩擦因数为_.若在木块上再施加一个与水平拉力F在同一竖直平面内的推力，而不改变木块的加速度的大小和方向，则此推力与水平拉力F的夹角为_.11.总

6、质量为M的热气球由于故障在空中以速度v0匀速下降.为了阻止继续下降，在t=0时刻，从热气球中释放了一个质量为m的沙袋.不计空气阻力，当t=_时，热气球停止下降，这时沙袋的速度为_.12.一辆小车在水平恒力F作用下，由静止开始在水平面上匀加速运动t1 s后撤去F，小车再经过t2 s停下.则小车加速阶段的位移s1与减速阶段的位移s2之比s1s2=_；小车牵引力F与所受的摩擦力Ff之比FFf=_.三、计算题（共36分）13.(12分)（2001年上海高考试题）如图1108所示，一质量为m的物体系于长度分别为l1、l2的两根细线上，l1的一端悬挂在天花板上，与竖直方向夹角为，l2水平拉直，物体处于平衡

7、状态.现将l2线剪断，求剪断瞬时物体的加速度.图1108(1)下面是某同学对该题的一种解法：解：设l1线上拉力为T1，l2线上拉力为T2，重力为mg，物体在三力作用下保持平衡T1cos=mg，T1sin=T2，T2=mgtan剪断线的瞬间，T2突然消失，物体即在T2反方向获得加速度.因为mgtan=ma，所以加速度a=gtan，方向与T2反方向.你认为这个结果正确吗?请对该解法作出评价并说明理由. (2)若将图1108中的细线l1改为长度相同、质量不计的轻弹簧，如图1109所示，其他条件不变，求解的步骤和结果与(1)完全相同，即a=gtan，你认为这个结果正确吗?请说明理由.图110914.(

8、12分)一弹簧秤的秤盘质量M=1.5 kg，盘内放一物体P，物体P的质量m=10.5 kg，弹簧质量不计，其劲度系数为k=800N/m，系统处于静止状态，如图11010所示.现给P施加一个竖直向上的力F，使P从静止开始向上做匀加速运动，已知在头0.2 s内F是变力，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)图1101015.（12分）2001年9月11日，美国遭受了历史上规模最大、损失最为惨重的恐怖主义袭击，恐怖分子劫持客机分别撞击了纽约的“世贸大楼”和华盛顿的“五角大楼”.其中一架客机拦腰撞到世贸大楼的南部塔楼第60层地方，并引起巨大爆炸，大约1 h后，南部

9、塔楼部分轰然倒塌（高约245 m），灰尘和残骸四处飞溅，300多名救援警察和消防人员没来得及逃生.我们不妨设置一个情境：当处于倒塌部分正下方的地面人员，看到一块质量约为4 103 kg的楼墙块竖直倒下的同时到作出反应开始逃离需0.2 s的时间，逃离的安全区域为离大厦100 m外（实际的安全区要更远）.设该坠落块与地面作用时间为0.05 s，不计空气阻力，g取10 m/s2.求：（1）地面人员要逃离大厦到安全区至少要以多大速度奔跑？（忽略人的加速时间，百米短跑世界记录为979）（2）该坠落块对地产生的平均作用力多大？（3）由于爆炸引起地表震动，设产生的纵波的传播速率vp=9.1 km/s,横波的

10、传播速率vs=3.1 km/s，设在某处的地震勘测中心记录到两种不同震感之间的时间间隔t0=5 s,那么观测记录者与震源之间的距离s为多少千米？参考答案一、1.AD 2.C 3.BC 4.D 5.AC 6.AC 7.CD8.A 以盘和重物为一个整体加以隔离，平衡时kL=（m+m0）g，k=.用手向下拉，弹簧共伸长L+L，弹力F=k（L+L）手的瞬时，根据牛顿第二定律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.隔离盘中物体，设盘对物体的支持力为N，由牛顿第二定律N-mg=ma故N=mg+ma=mg+mg=（1+）mg，向上.二、9.2

11、010.= =arctan根据牛顿第二定律由F-mg=ma得=加力F后，水平加速度不变，有F+Fcos-(mg+Fsin)=ma与上式联立得=arctan说明推力方向只能与水平方向成角向下，因施推力后加速度不变，则必有Fcos=Fsin.即得tan=所以=arctan11.t=(M-m)v0/mg; 12.t1t2;FFf=(t1+t2)t1三、13.因为l2被剪断瞬间，l1上的张力大小发生了变化.（1）错.因为l2被剪断的瞬间，弹簧的长度来不及发生变化，力T1的大小和方向都不能突变，（2）对.14.依题意，0.2 s后P离开了托盘，0.2 s时托盘支持力恰为零，此时加速度为：a=（F大-mg

12、）/m(式中F大为F的最大值)此时M的加速度也为a.a=（kx-Mg）/M所以kx=M（g+a）原来静止时，压缩量设为x0，则：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最大值为168 N.刚起动时F为最小，对物体与秤盘这一整体应用牛顿第二定律得F小+kx0-（m+M）g=（m+M）a代入有：Fmin=（m+M）a=72 NF最小值为72 N.15.（1）坠落物做自由落体运动的时间：h=gt2落地速度v0=gt地面人员逃离时间t=t-0.2逃离速度

13、v=求得t=7 s v0=70 m/s v=10.3 m/s(2)根据牛顿运动定律可知：(F-mg)=ma=m求得F=5.64106 N(3)震动同时产生传播，则由匀速运动知求得s=23.1 km 第 11 次课后作业学生姓名： 1.在水平地面上运动的小车车厢底部有一质量为m1的木块，木块和车厢通过一根轻质弹簧相连接，弹簧的劲度系数为k.在车厢的顶部用一根细线悬挂一质量为m2的小球某段时间内发现细线与竖直方向的夹角为，在这段时间内木块与车厢保持相对静止，如图3310所示不计木块与车厢底部的摩擦力，则在这段时间内弹簧的形变为() A伸长量为 B压缩量为C伸长量为 D压缩量为2. 如图3311所示

14、，在光滑的水平面上，A、B两物体的质量mA2mB，A物体与轻质弹簧相连，弹簧的另一端固定在竖直墙上，开始时，弹簧处于自由状态，当物体B沿水平向左运动，使弹簧压缩到最短时，A、B两物体间作用力为F，则弹簧给A物体的作用力的大小为()AF B2F C3F D4F3如右图所示，车厢里悬挂着两个质量不同的小球，上面的球比下面的球质量大，当车厢向右做匀加速运动时(空气阻力不计)，两个小球稳定后所处的位置下列各图中正确的是()4.如图3312所示，在光滑的水平面上放着紧靠在一起的A、B两物体，B的质量是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的单位是s)从t0开始计时，则

15、()AA物体在3 s末时刻的加速度是初始时刻的倍Bt4 s后，B物体做匀加速直线运动Ct4.5 s时，A物体的速度为零Dt4.5 s后，A、B的加速度方向相反5. 如图，风洞实验室中可产生水平方向的、大小可调节的风力。现将一套有小球的细直杆放入风洞实验室，小球孔径略大于细杆直径。（1）当杆在水平方向上固定时，调节风力的大小，使小球在杆上做匀速运动，这时小球所受的风力为小球所受重力的0.5倍，求小球与杆间的滑动摩擦因数。（2）保持小球所受风力不变，使杆与水平方向间夹角为37，并固定，则小球从静止出发在细杆上滑下距离s所需时间为多少？（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 t

38、ropopause),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 s

39、ame 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 Englands Josh Charnley in the opening game of the tournament.That could be classed as a weakness, a team under-cooked -

40、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, especially on their own goal-line, completing sets and a good kick-chase. Theyve been great at all the unglamorous stuff t

41、hat 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, Cameron Smith and either Billy Slater or Greg Inglis at full-back they have a spine that is unmatched in rugby league. The

42、y 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 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.第 13 页 共 13 页