磁悬浮列车问题.doc

磁悬浮列车磁悬浮列车问题题一：（选自2004年普通高等学校招生全国统一考试考试大纲样题） 1有一种高速磁悬浮列车的设计方案，是在每节车厢底部安装强磁铁（磁场方向向下），并在两条铁轨之间沿途平放一系列线圈。下列说法中不正确的是： A 当列车运动时，通过线圈的磁通量会发生变化 B 列车速度越快，通过线圈的磁通量变化越快 C 列车运动时，线圈会产生感应电流 D 线圈中感应电流的大小与列车的速度无关 2磁悬浮列车在行进时会浮在轨道上方，从而可高速行驶。可高速行驶的原因是：列车浮起后： A 减少了列车的惯性 B 减少了地球对列车的引力 C 减少了列车与铁轨间的摩擦力 D 减少了列车所受的空气阻力3假设列车从静止开始做匀加速运动，经过500m的路程后，速度达到360km/h。整个列车的质量为1.00105kg，如果不计阻力，在匀加速阶段，牵引力的最大功率是 A 4.67106KW B 1.0105KW C 1.0108KW D 4.67109KW题二：（选自中学物理综合讲座）一种磁悬浮列车的原理如图所示，在水平面上，两根平行直导轨间有竖直方向且等距离的匀强磁场B1和B2,导轨上有金属框abcd。当匀强磁场B1和B2同时以V沿直导轨向右运动时，金属框也会沿直导轨运动，设直导轨间距为L=0.4m，B1=B2=1T，磁场运动的速度V=5m/s，金属框的电阻R=2，试求：（1）金属框为什么运动？若金属框不受阻力时，金属框如何运动？ （2）当金属框始终受到f=1N的阻力时，金属框最大速度是多少？ （3）当金属框始终受到1N阻力时，要使金属框维持最大速度，每秒种需消耗多少能量？这些能量是谁提供的？ 题三：（选自2000年高校招收保送生综合能力测试上海卷试题） 一般情况下，金属都有电阻，电阻是导体的属性之一。当条件发生改变时，其属性也会发生改变。 1实验表明，某些金属当温度降低到某一定值时，其电阻突然降为零，这种现象叫做_现象，这一特定温度称为临界温度，其值与金属材料有关。2将某种液态物质倒入金属盘后，能使金属盘达到临界温度，在金属盘上方释放一永磁体，当它下落到盘上方某一位置时即产生磁悬浮现象，试根据下表列出的几种金属的临界温度和几种液态物质的沸点数据，判断所倒入的液态物质应是_，金属盘的材料应是_ 。金属临界温度（k）液态物质沸点（K） 铱014液氦41锌075液氮770 铝120液氧900 锡372液态甲烷1115 铅720液态二氧化碳19453利用上述现象，人们已经设计制造磁悬浮高速列车。列车车厢下部装有电磁铁，运行所需槽形导轨的底部和侧壁装有线圈，用以提供_。这种列车的运行速度是一般列车运行速度的3 4倍，能达到这样高速的原因是_。 题四：给你一个异常的艰巨任务，要求你必须说服国家领导人同意修建京沪磁悬浮线路，你准备怎么演说？如果要求你说服国家领导人放弃磁悬浮技术采用轮轨技术，你又准备怎么演说？试一试，锻炼你的思辩能力。题五：比较德国和日本的两种磁悬浮技术，你认为哪种有更广泛的应用前景？为什么？题六：阅读理解Maglevs (Magnetically levitated trains)IntroductionThe principal of a Magnet train is that floats on a magnetic field and is propelled by a linear induction motor. They follow guidance tracks with magnets. These trains are often refered to as Magnetically Levitated trains which is abbreviated to MagLev. Although maglevs dont use steel wheel on steel rail usually associated with trains, the dictionary definition of a train is a long line of vehicles travelling in the same direction - it is a train. How it worksA maglev train floats about 10mm above the guidway on a magnetic field. It is propelled by the guidway itself rather than an onboard engine by changing magnetic fields (see right). Once the train is pulled into the next section the magnetism switches so that the train is pulled on again. The Electro-magnets run the length of the guideway. What is the advantage of Maglev? Well it sounds high-tech, a floating train, they do offer certain benefits over conventional steel rail on steel wheel railways. The primary advantage is maintanance. Because the train floats along there is no contact with the ground and therefore no need for any moving parts. As a result there are no components that would wear out. This means in theory trains and track would need no maintanence at all. The second advantage is that because maglev trains float, there is no friction. Note that there will still be air resistance. A third advantage is less noise, because there are no wheels running along there is no wheel noise. However noise due to air disturbance still occurs. The final advantage is speed, as a result of the three previous listed it is more viable for maglev trains to travel extremely fast, ie 500km/h or 300mph. Although this is possible with conventional rail it is not economically viable. Another advantage is that the guidway can be made a lot thicker in places, eg after stations and going uphill, which would mean a maglev could get up to 300km/h (186mph) in only 5km where currently takes 18km. Also greater gradients would be applicable. What is the disadvantages with MaglevThere are several disadvantages with maglev trains. Maglev guide paths are bound to be more costly than conventional steel railways. The other main disadvantage is lack with existing infrastructure. For example if a high speed line between two cities it built, then high speed trains can serve both cities but more importantly they can serve other nearby cities by running on normal railways that branch off the high speed line. The high speed trains could go for a fast run on the high speed line, then come off it for the rest of the journey. Maglev trains wouldnt be able to do that, they would be limited to where maglev lines run. This would mean it would be very difficult to make construction of maglev lines commercially viable unless there were two very large destinations being connected. Of the 5000km that TGV trains serve in France, only about 1200km is high speed line, meaning 75% of TGV services run on existing track. The fact that a maglev train will not be able to continue beyond its track may seriously hinder its usefulness.Although I havent seen anywhere a solution could be to put normal steel wheels onto the bottom of a maglev train, which would allow it to run on normal railway once it was off the floating guideway. Are maglevs really more enviromentally friendly?In terms of energy consumption maglev trains are slightly better off than conventional trains. This is because there is no wheel-on-rail friction. That said the vast majority of resistive force at high speed is air resistance (often amounting to several tons), which means the energy efficiency of a maglev is only slightly better than a conventional train. German engineers claim also that a maglev guideway takes up less room and because greater gradients are acceptable there is not so much cuttings and embankments meaning a new guideway would be less disruptive to the countryside than a new high speed conventional railway. Will Maglevs replace conventional trains?Provided maglev can be proved to be commerciably viable (which has not yet been done) it should be a success. Most people have their eyes on Germany, where the first maglevs will run in commercial service. This may decide whether or not maglevs will be used across the world. Maglev may become the preferred path for new high speed railway lines although it would depend whether or not services were needed to stretch beyond a high speed line. For example, if you have 300km of conventional track between two cities cleared for over 200km/h but there was a 60km long section only cleared for 80km/h then it would make sense to build a new high speed (300km/h) line for the 60km distance. If a maglev train were to be used a track 300km long would have to be built. However if there is no existing rail network (only the case in the USA) then it makes sense to build a maglev line. Whether or not new railway lines stopped being built in favour of maglevs, one thing is certain, there is 31932km of track in the UK, 34449km in France and 40726km Germany, no one is going to convert all of this into maglev track, conventional trains are here to stay for a long time.Maglevs in commercial service.In the mid 1980s, Britain was the first country to introduce a maglev service. It was to link two terminals at Birmingham airport, about 400meters long and a top speed of about 10mph (16km/h). However it was recently replaced with a bus service due to the difficulty of getting spare parts. Germany is the only country with solid plans for a maglev railway which will link Berlin with Hamburg in 2005. This will be high speed called the transrapid project. There are no other examples of maglev in use, even thought the technology has been around since the 1960s. This has meant most have lost interest in the idea, especially now when very high speeds are achievable with conventional steel rail technology.Maglevs under testCountries who tested maglev trains are the USA, Japan and Germany. However nowerdays the USA is less interested in maglev. Japan has built two maglev lines, the first in the 1960s and the second in 1996. The first was to test the basic theory of maglev the second is going for more advanced things such as high speed tests with the MLX01, and set a speed record of 550km/h (344mph) in early 1998. Maglevs（磁悬浮列车） 介绍 磁列车的原理是在磁场中悬浮并且有电感引擎驱动。他们行驶在有磁力的轨道上。这些列车通常被称为磁悬浮列车，简称Maglev。虽然Maglevs并没有普通火车所具有的在钢轨上行驶的轮子，字典中对火车的解释是向着同一方向跑的长长的交通工具，那就是火车。 磁悬浮列车在充满磁场的导轨上浮起10毫米。它不是由内置引擎驱动，而是由变化的磁场和导轨本身驱动（见右图）。一旦车进入下一个部分，磁场改变使车继续行驶。电磁贯穿整个导轨。Maglevs的优势是什么呢？它听起来像高科技，一个浮动的火车，它们确实比传统的钢轨火车有更多优势。最主要的就是它的耐久性。因为火车浮动前进，和地面没有接触所以就没有设置活动部件的必要。因此也就没有哪个部件因磨损而坏掉。这意味着理论上车和轨道根本不需要维修。第二个优点由于磁悬浮列车是浮起的，所以没有摩擦。但要注意空气阻力始终存在。第三个优点是噪音小，因为没有轮子，所以也就没有轮子带来的噪音。然而和空气碰撞的噪音始终存在。最后一个优点就是速度，由于前面所列举的三个优点，磁悬浮列车更有可能以极快的速度运行，500千米每小时或300千米每小时。尽管这对传统的火车也可行，但是经济上不合算。还有一个优点就是导轨可以做的更厚，比如在进出站或上下山时，这意味着磁悬浮列车可以在5千米内达到300千米每小时（186英里每小时），而现在的火车达到同样速度需要用18千米。并且更大的坡道也可以使用。磁悬浮列车的缺点有哪些 磁悬浮列车也有几项缺点。磁悬浮列车导轨比传统导轨造价更高。另一个主要问题就是缺少广泛的使用。举个例子，如果一条高速铁路建在两个城市之间，那么这条高速路可以为两个城市服务，同时更重要的是它们可以为沿途的城市运送旅客，只要走那些普通的铁路支线即可。高速火车可以以很快的速度行驶在高速铁路上，然后在减速行驶在支线上。磁悬浮列车就不同了，它们被限制在磁悬浮轨道上。这意味着在经济上使磁悬浮列车轨道的建设可行是很困难的，除非是连接两个大型的目的地。在法国TGV列车所经过的5000千米路线中，只有1200千米是高速线，说明75的TGV列车行驶在已建好的（普通）铁路上。磁悬浮列车不能行驶在磁悬浮轨道之外这个事实严重地限制了磁悬浮列车的用武之地。 尽管我没见过哪里想出了能让将普通轨道作为磁悬浮列车的导轨，使磁悬浮列车在下了磁悬浮导轨后还能行驶在普通轨道上的解决办法。磁悬浮列车更环