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1、学号:10403215常州大学论文(2010届)题目浅谈“香蕉球”的力学原理学生学院机械工程学院专业班级校内指导教师专业技术职务校外指导老师专业技术职务二○一三年六月浅谈“香蕉球”的力学原理摘要:本文从绿茵场上神秘莫测的“香蕉球”谈起,运用动力学对球的运动和受力进行分析。然后从流体力学角度分析了“香蕉球”产生的原理。关键词:香蕉球;伯努利方程;流体力学DiscussiononMechanicalPrincipleofBananaBallAbstract:Thearticletalksaboutmagicalbanana
2、ballonthecourt,Usingdynamicstosolvethemovementoftheballandtheanalysisofforcesonit,andthenfocusingontheprincipleofthebananaballfromafluidmechanicsstandpoint.KeyWords:bananaball;Bernoulli'sEquation;hydromechanicsI摘要·················································
3、···················Ⅰ目次····································································II1引言··································································12伯努利原理····························································22.1伯努利原理·························
4、·································22.2伯努利原理在足球中的应用············································23香蕉球的受力分析······················································33.1粘滞阻力····························································3II3.2压差阻力···························
5、·································33.3附加作用力··························································44流体力学原理·························································54.1“香蕉球”的流体力学原理············································5参考文献································
6、································6IIII1引言“香蕉球”,是足球运动技术名词(英语bananaball)。指足球踢出后,球在空中向前并作弧线运行的踢球技术。弧线球常用于攻方在对方禁区附近获得直接任意球时,利用其弧线运行状态,避开人墙直接射门得分。当代足坛帅哥大卫·贝克汉姆就是射“香蕉球”的好手。他主罚任意球时,往往使出“香蕉球”的绝招,让对方守门员无所适从。下面我们试着探讨这个奇妙的现象。第5页共6页2伯努利原理2.1伯努利原理伯努利原理认为:“在流水或气流里,如果流速小,对旁侧的压力
7、就大,如果流速大,对旁侧的压力就小。”足球队员用脚踢球时,只踢球的一小部分,把球“搓”起来,球受力,就发生旋转,而当球在空中高速旋转并向前飞行时,它属于刚体的一般运动,它包括了刚体的平移、定轴转动、定点运动等。作为一般运动的刚体上的任一点的速度,等于基点的速度与该点随刚体绕基点转动速度的矢量和。球的两侧一边速度大,一边速度小,相对讲,空气在球的两侧也就一边流速大,一边流速小。根据伯努利原理,球就受到了一个横向的压力差,这个压力差,使球向旁侧偏离,而球又是不断向前飞行着,在这种情况下,足球同时参与了两个直线运动,便沿一条
8、弯曲的弧线运行了。伯努利原理在生活中有很多神奇的现象,两张纸平行放置,用口想两纸中间吹气,神奇的现象出现了,你会发现两纸不会分开而是靠在一起。也许你会很惊奇,当时,看到伯努利之后你就明白是怎么回事了。伯努利方程式,实际上是流体运动中的功能关系式,即单位体积流体的机械能的增量等于压力差所做的功。必须指出,伯努利方程式右边的常量,对于