用作图法来表示力的大小、方向、作用点这三要素,就叫力的图示。为了帮助同学们减少在作力的图示时所存在的种种失误,我向同学们介绍一种比较系统的作力的图示的方法——“五定法”(即一定标、二定点、三定线、四定长、五定向)。一定标——选定作图的标度,即单位长度的线段表示多大的力。一个物体受几个力时,应当兼顾各个力的大小,一般采用这几个力的最大 The three elements of force, size, direction, and point of action are used as diagrams to illustrate the force. In order to help students reduce all kinds of mistakes in their graphic representations, I introduced the students to a more systematic way of figuring out the “five sets of laws” (ie, certain criteria, two fixed points, three Lines, four fixed lengths, five oriented). A certain target—the scale of the selected map, ie, how much force is represented by a line segment per unit length. When an object is subjected to several forces, the strength of each force should be taken into consideration. Generally, the maximum force of these forces is used.