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在力学部分,我们常会遇到一个或多个物体同时受到几个力的情形.已知条件不多,要求的量不少,使我们无从下手,难以适从.如果我们确定研究对象,并把它隔离开来进行受力分析,找出各力之间的联系,很多难题都能迎刃而解.并能收到事半功倍之效.例1:将塑料球和木块用细绳相连放入水中时,木球露出水面的体积为它自身体积的3/8,如图1所示.当把细绳剪断后,塑料球沉底,木球露出水面的体积为自身体积的1/2,这
In the mechanics part, we often encounter situations where one or more objects are subjected to several forces at the same time. Known conditions are not many, and the quantity required is so many that we have no way to start, it is difficult to adapt. If we identify the research object, and put It isolates and analyzes forces and finds links between forces. Many problems can be solved and they can do more with less. Example 1: When plastic balls and blocks are attached to water with a string, The volume of water exposed on the surface of the wooden ball is 3/8 of its own volume, as shown in Figure 1. When the string is cut, the plastic ball sinks and the volume of the exposed surface of the ball is 1/2 of its own volume.