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1、(完整word版)Lesson2ForcesandTheir专业英语Lesson 2 Forces and TheirEffectsTerminologyText tourTerminologyCompressiveServing to or able to compress压缩的：起压缩作用或能够压缩的TurningThe shaping of metal or wood on a lathe车削：用车床将金属或木材加工成型的过程Lathe 车床 Rectilinear,rektiliniMoving in， consisting of, bounded by， or characteriz
2、ed by a straight line or lines：直线的：以直线运动的，向直线组成的，以直线为边的，具有直线之特点的 micrometer 千分尺ThreadA helical or spiral ridge on a screw, nut, or bolt螺纹:螺钉、螺母或螺栓上螺旋型的凸棱ShaperText tourA study of any machine or mechanism shows that each is made up of movable parts. These parts transform a given motion to a desired m
3、otion. In other words， these machines perform work. Work is done when motion results from the application of force。 Thus, a study of mechanics and machines deals with forces and the effects of forces on bodies。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
4、体的影响。A force is a push or pull. The effect of a force either changes the shape or motion of a body or prevents other forces from making such changes。 Every force produces a stress in the part on which it is applied。 Forces may be produced by an individual using muscular action or by machines with me
5、chanical motion。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。Forces are produced by physical or chemical change, gravity， or changes in motion. When a force is applied which tends to stretch an object, it is called a tensile force. A part experiencing a tensil
6、e force is said to be intension. A force can also be applied which tends to shorten or squeeze the object。 Such a force is a compressive force。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.A third force is known as a torsional force， or a torque since it tends to
7、twist an object. Still another kind of force, which seems to make the layers or molecules mlikjuls of a material slide or slip on one another， is a shearing force.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.Each of these forces may act independently or in combination. For
8、example, a downward force applied on a vertical steel beam tends to compress the beam. If this beam is placed in a horizontal position and a load is applied in the middle, the bottom of the beam tends to stretch and is in tension. At the same time， the top area is being pushed together in compressio
9、n. If the compressive and tensile forces are greater enough to make the layers of the material slide upon each other, a shearing force results。参考译文:这些力都可以单独或者组合起来起作用。例如,一个向下的力施加在垂直钢梁上会压缩它。如果将梁水平放置，载荷施加在梁的中央，则梁的下方会伸长而受拉。同时梁的上方被压缩而受压.如果压力和拉力足够大到使材料的各层产生相对滑移，则会出现剪切力。The turning of a part in a lathe is
10、another example of several forces in action （as shown in Figure 1）.1Fig。 1 The turning of a part in a lathe1。 turning of a part 这里指“对一个零件进行车削加工”。全句译为:几个力同时作用的另外的一个例子是在车床上对零件进行车削加工（如图1所示)。As the work revolves and the cutting tool moves into the work, the wedgingaction of the cutting edge produces a s
11、hear force. This force causes the metal to seem to flow off the work in the form of chips.22. chip 这里指“切屑。work 这里指“工件，即 workpiece ”。全句可译为：工件旋转时刀具切入工件,切削刃的楔入动作产生剪切力。这个力使得金属看起来像以切屑的形式从工件上流出来一样.If this workpiece is held between the centers of the lathe, the centers exert a compressive force against the
12、 work。33. centers of the lathe 意为“车床的两个顶尖”.全句可译为：如果一个工件被安装在车床的两个顶尖The lathe dog which drives the work tends to produce a shearing force。 The pressure of the cutting tool against the work produces tension and compression， as well as a shearing action.参考译文:驱动工件的车床夹头会产生一个扭转力。刀具顶在工件上的压力会同时产生拉力和压力,以及剪切作用
13、。Considerable attention is given to the action of centrifugal force in grinding wheels. That is, the bonding agent that holds the abrasive particles on the wheel must be stronger than the forces which tend to make the revolving wheel fly apart at high speeds. For this reason， the speed of a grinding
14、 wheel should not exceed the safe surface speed limit specified by the manufacturer。 Centrifugal force increases with speed。参考译文：对磨削用的砂轮来讲离心力的影响要特别给以关注。即把磨料颗粒粘合在砂轮上的粘合剂它的粘合力必须大于使高速旋转的砂轮分崩离析的离心力。因此，砂轮的转速不能超过制造商给定的安全表面速度限制。离心力随转速的增加而增大。The principles of centrifugal force are used in the design of cent
15、rifugetype machines. Some centrifuges are used to separate chemicals； others are used to remove impurities in metals by centrifugal casting processes.Centrifugal force principles are also used in common appliances such as clothes dryers and in devices to control motor speeds and accelerate moving ma
16、chines.参考译文：离心力的这种原理用在离心型机器的设计中。一些离心分离机用于分离化学制品;还有的通过离心铸造工艺分离金属中的杂质。离心力作用也有普通的应用如干衣机、控制发动机转速的装置以及用于加速运动的机器。Centripetal force causes an object to travel in circular path. This action is caused by the continuous application of forces which tend to pull the object to the center. In other words, the inward force which resists the centrifugal force is called the ce
