Lesson 2 Forces and Their

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1、专业英语18Lesson2ForcesandTheirEffectsTerminologyTexttourTerminologyCompressiveServingtoorabletocompress压缩的：起压缩作用或能够压缩的TurningTheshapingofmetalorwoodonalathe车削：用车床将金属或木材加工成型的过程Lathe车床Rectilinear[,rekti'liniə]Movingin,consistingof,boundedby,orcharacterizedbyastraightlineorlines:直线的：以直线运动的，向直线组成的，以直线为

2、边的，具有直线之特点的micrometer千分尺ThreadAhelicalorspiralridgeonascrew,nut,orbolt螺纹：螺钉、螺母或螺栓上螺旋型的凸棱ShaperTexttourAstudyofanymachineormechanismshowsthateachismadeupofmovableparts.Thesepartstransformagivenmotiontoadesiredmotion.Inotherwords,thesemachinesperformwork.Workisdonewhenmotionresultsfromtheapplicati

3、onofforce.Thus,astudyofmechanicsandmachinesdealswithforcesandtheeffectsofforcesonbodies.参考译文：研究表明机器或者机构都是由若干运动零件组成的。这些零件将给定运动转换成目标运动。换句话说，这些机器做功。因为力的作用产生运动而做功。因此，力学和机械（学）研究力以及力对物体的影响。Aforceisapushorpull.Theeffectofaforceeitherchangestheshapeormotionofabodyorpreventsotherforcesfrommakingsuchchang

4、es.Everyforceproducesastressinthepartonwhichitisapplied.Forcesmaybeproducedbyanindividualusingmuscularactionorbymachineswithmechanicalmotion.参考译文：力分为推力和拉力，力可以改变物体的形状或运动状态或者防止其他力作这样的改变。施加在零件上的力会在其内部产生应力。力可以由个人的肌肉活动或者由机器的机械运动产生。Forcesareproducedbyphysicalorchemicalchange,gravity,orchangesinmotion.

5、Whenaforceisappliedwhichtendstostretchanobject,itiscalledatensileforce.Apartexperiencingatensileforceissaidtobeintension.Aforcecanalsobeappliedwhichtendstoshortenorsqueezetheobject.Suchaforceisacompressiveforce.参考译文：力由物理或化学变化、地心引力或者运动变化产生。当力用于拉伸物体时叫拉力。零件受拉力作用被称为受拉（处于拉伸状态）。力也可用于缩短或挤压物体，这种力叫压力。Ath

6、irdforceisknownasatorsionalforce,oratorquesinceittendstotwistanobject.Still18anotherkindofforce,whichseemstomakethelayersormolecules['mɔlikjuls]ofamaterialslideorslipononeanother,isashearingforce.参考译文：（我们知道的）第三种力是扭转力，或者叫扭矩，因为它会扭曲物体。还有另一种力，它似乎会使材料的各层或分子间产生相对滑移，称为剪切力。Eachoftheseforcesmayactindepen

7、dentlyorincombination.Forexample,adownwardforceappliedonaverticalsteelbeamtendstocompressthebeam.Ifthisbeamisplacedinahorizontalpositionandaloadisappliedinthemiddle,thebottomofthebeamtendstostretchandisintension.Atthesametim