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一、重点、难点讲解1.力的合成与分解的特征。(1)等效性:根据需要可以将几个力用一个力等效替换,也可以将一个力用几个力等效替换。(2)替代性:力在被替代后,就不能再参与计算。在分析同一个问题时,合矢量和分矢量不能同时使用,考虑了合矢量就不能再考虑分矢量,考虑了分矢量就不能再考虑合矢量。(3)虚拟性:力的合力和分力都是实际不存在的力。2.力的按效果分解。(1)首先,根据力的作用效果确定两个分力的方向;其次,根据已知力和两个分力方向作平行四边
First, focus, difficult to explain 1. Force synthesis and decomposition characteristics. (1) Equivalence: Several forces can be equivalently replaced with one force as required, and one force can also be equivalently replaced with several forces. (2) Substitution: After the force is replaced, it can no longer participate in the calculation. When analyzing the same problem, the combined vector and the divided vector cannot be used at the same time. Considering the combined vector, the split vector can no longer be considered. Considering the split vector, the combined vector cannot be considered. (3) Virtuality: Forces and forces of force are forces that do not actually exist. 2. Decomposition of force by effect. (1) First, the direction of the two component forces is determined according to the effect of the force; secondly, the parallel force is determined based on the known force and the two component directions.