很多物理量都有可加性。根据可加性,把复杂问题化为简单特殊问题并求出其结果,然后进行叠加(如代数的、矢量的叠加),即可求出复杂问题的结果。这是解题的一种重要技巧。下面举几个例子作一分析,介绍。例1.在一块半径为r的均质圆板上挖去一个半径为r′的小圆孔,求剩下部分的重心位置。小圆孔的圆心距圆板中心是r/2[如图1(b)]。挖去小圆孔后剩下部分加上 Many physical quantities have additivity. According to the additivity, the complex problem can be transformed into a simple special problem and the result can be obtained. Then the superposition (such as algebraic, vector superposition) can be used to find the result of a complex problem. This is an important technique for problem solving. Here are some examples for an analysis and introduction. Example 1. Draw a small round hole with a radius of r’ on a homogeneous circular plate with a radius of r to find the rest of the center of gravity. The center of the small round hole is r/2 from the center of the circular plate [Fig. 1(b)]. After removing the small hole, add the rest