速度分解是中学物理教学中的一个难点。从理论上讲,速度分解和其他矢量的分解一样是任意的,即一个速度可以分解为无数对大小、方向都不同的分量。学生在解决具体问题时,对无数种分解中究竟选择哪一种没有把握,分不清哪个是合速度,哪个是分速度。因此在全国统考和中学物理竞赛中有关这方面试题的错误率很高,甚至有的出版的书籍上也会出现这方面的错误。 Speed ​​decomposition is a difficult point in middle school physics teaching. Theoretically speaking, velocity decomposition is as arbitrary as the decomposition of other vectors, that is, a velocity can be decomposed into innumerable components with different sizes and directions. When students solve specific problems, they are unsure of which of the countless kinds of decomposition they choose, and they cannot tell which one is the combined speed and which is the speed. Therefore, the error rate in the national examinations and high school physics competitions on this topic is high, and even some published books will appear in this area.