长度的测量和基本数据处理讲义.doc

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1、长度的测量和基本数据处理【实验目的】1、理解游标卡尺、螺旋测微计和移测显微镜的原理，掌握它们的使用方法；2、练习有效数字运算和误差处理的方法。【实验仪器和用品】游标卡尺（0125mm，0.02mm）、螺旋测微计（025mm，0.01mm）、移测显微镜（JCD3，0.01mm）、空心圆管、小钢球等。【实验原理】1、游标卡尺的构造原理及读数方法游标卡尺分主尺和游标（副尺）两部分。主尺上刻有标准刻度125mm。游标上均匀刻有50个分度，总长度为49mm，游标上50个分度比标准的50mm短1mm，1个分度比标准的1mm短mm，即0.02mm，这0.02mm就是游标卡尺的最小分度值（即精度）。游标卡尺的

2、卡口合并时，游标零线与主尺零线恰好对齐。卡口间放上被测物时，以游标零线为起点往前看，观察主尺上的读数是多少。假设读数是Xmm多一点，这“多一点”肯定不足1mm，要从游标上读。此时，从游标上找出与主尺上某刻度最对齐的一条刻度线，设是第n条，则这“多一点”的长度应等于0.02nmm，被测物的总长度应为L=(x+0.02n)mm。用这种规格的游标卡尺测量物体的长度时，以“mm”为单位，小数点后必有两位，且末位数必为偶数。游标上每5小格标明为1大格，每小格读数作0.02mm，每大格就应读作0.10mm。从游标零线起往后，依次读作0.02mm，0.04mm，0.06mm，直至第5小格即第1大格读作0.1

3、0mm。0670345主尺游标图1-5再往后，依次读作0.12mm，0.14mm，0.16mm，直至第2大格读作0.20mm。后面的读数依此类推。游标卡尺不需往下估读。如图1-5应读作61.36mm或6.136cm2、螺旋测微器的构造原理及读数方法螺旋测微计主要由弓形体、固定套筒和活动套筒（微分套筒）三部分构成。螺旋测微计的测微原理是机械放大法。固定套筒上有一条水平拱线叫读数基线。基线上边是毫米刻度线，下边是半毫米刻度线。螺旋测微计的螺距是0.5mm，活动套筒每转动一周，螺杆就前进或者后退0.5mm。活动套筒的边缘上均匀刻有50个分度，每转动一个分度，螺杆就前进或者后退mm即0.01mm。这0

4、.01mm就是螺旋测微计的最小分度值（即精度）。实际测量时，分度线不一定正好与读数基线对齐，因此还必须往下估读到0.001mm。可见，用螺旋测微计测量物体的长度时,以“mm”为单位，小数点后必有三位。读数时，先从固定套筒上读出大于半毫米的大数部分，再从活动套筒的边缘上读出小于半毫米的部分，二者之和就是被测物体的总长度。这其中一定要注意观察半毫米刻度线是否露出来了。如图1-6(a)应读作5.272mm，图1-6(b)应读作5.772mm.05固定套筒图1-6（a）3025微分套筒05固定套筒图1-6 (b)3025微分套筒图1-7（a）主刻度尺读数 图1-7（b）测微鼓轮读数使用螺旋测微计之前，

5、必须先检查零点读数。先转动大棘轮使螺杆前进，当螺杆快要接触测砧时就应转动后面的小棘轮，听到“嗒嗒”声立即停止。如果此时活动套筒上的零线正好对齐读数基线，零点读数就记作0.000mm，如果零线在读数基线以上，零点读数记作负，反之为正。每一次测量的直接读数减去零点读数才是真正的测量值，即测量值=直接读数零点读数。例如零点读数是-0.002mm，直接读数是5.272mm，则测量值=5.272-（-0.002）=5.274（mm）。3、读数显微镜的构造原理及读数方法移动方向图1-8读数显微镜是将显微镜与螺旋测微计结合起来的长度精密测量仪器。其测微原理是光学放大法和机械放大法的综合。活动螺杆与显微镜筒通

6、过螺旋相互啮合，转动活动螺杆右端的鼓轮，就可以使显微镜左右平移。测微螺旋的螺距为1mm，鼓轮边缘上均匀刻有100个分度，每转动一个分度镜筒就向左或向右平移0.01mm。所以读数显微镜的最小分度值也是0.01mm，读数时也要往下估读到0.001mm。具体测量步骤是：（1）调节目镜，看到清晰的十字叉丝，并将叉丝调正；（2）将被测物平放到载物台上，并在镜筒的正下方，使被测长度的方向与镜筒平移的方向平行，然后调节镜筒升降旋钮，使镜筒缓慢的上升或下降，进行调焦，直到看清物体的像，无视差；（3）转动鼓轮，平移镜筒，当叉丝的竖丝与物像的始端相切时，记下初读数X1，读数方法如图1-7（a）和1-7（b）所示。

7、继续沿同一方向平移镜筒，当竖丝与物像的末端相切时，记下末读数，则待测长度；（4）读数时，从固定刻度上读出大于1mm部分，从鼓轮边缘上读出小于1mm的部分，二者之和就是X1或X2的值。测量时应注意的问题是，两次读数时镜筒必须是向同一个方向平移，不得移过了头又移回来，这样会产生空程误差。如果不小心移过了头，必须多往回退一些距离，再重新沿原方向平移，对准被测点。如果简单地概括读数显微镜的原理和使用方法，就是“综合放大，同向平移，求差”【实验内容与要求】1、用读数显微镜测量给定刻线的宽度，重复测量6次。2、用螺旋测微计测量小钢球的直径，沿不同径向测6次（注意：使用前应记录螺旋侧微计的零点读数）3、用游

8、标卡尺测量空心圆管的外径、内径和高，重复测量6次。4、计算给定刻线的宽度和不确定度。5、计算钢球的体积和不确定度。6、计算空心圆管的体积。【实验注意事项】1、注意保护游标卡尺的卡口不被磨损，轻轻卡住即可读数，不能将被测物在卡口内移动，不能跌。2、使用螺旋测微计时，当螺杆与被测物相距较近时就要转动尾部的小棘轮，听到“嗒嗒”声应立即停止。实验结束时，螺杆和测砧之间应留有小缝隙，不能拧死，以防热膨胀压坏精密螺丝。3、使用移测显微镜时，同一组读数应为沿同一方向平移读得的结果，否则会产生空程误差。镜头不能用手触摸。调焦时上、下移动筒一定缓慢，千万不能压坏物镜或被测物。【数据记录与处理】表一 给定刻线宽度

9、的测量 读数显微镜的仪器误差次序项目123456待添加的隐藏文字内容2= = = = = mm表二 钢球直径的测量 仪器误差=0.004 零点读数 次序123456平均值不确定度直读值（）测量值（）= = = = 表三 圆管体积的测量 游标卡尺的仪器误差=0.02。次序项目123456平均值外径内径 高= 【思考题】1、10分度和20分度的游标卡尺，最小分度值分别是多大？读数的末位有什么样的特点？2、比较一下游标卡尺和螺旋测微计，二者的读数方法有什么不同？Winger Tuivasa-Sheck, who scored two tries in the Kiwis 20-18 semi-fin

10、al 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 Australia have not conceded a try since Josh Charnleys effort in

11、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 player of the year Sonny Bill Williams who has attracted the

12、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 every award back in a heartbeat just to get across the lin

13、e 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 League match at Chelsea on Sunday.I am going to be at the match

14、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 behaviour of their fans duringCitys 2-1 win.Michel Platini, presi

15、dent 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 insults from fans of CSKA. Baumgartner the disappointing news

16、: 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 and limited cloud cover. The balloon, with capsule attached,

17、 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 commercial airliners (5.6 miles/9.17 kilometers) and into the

18、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 th

19、ey 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 Englands Josh Charnley in the opening game of the tournament

20、.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, especially on their own goal-line, completing sets and a good

21、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, Cameron Smith and either Billy Slater or Greg Inglis at full-b

22、ack 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 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.