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本章是九年级上册的起始章,包含的知识点、物理概念比较多,我们把它分成简单机械、功和功率、机械效率三个单元来分别解析其中的典型问题。一、简单机械典型问题解析例1关于力臂,下列说法中正确的是()A.从动力作用点到支点的距离叫做动力臂B.力臂就是杠杆的长度C.从支点到阻力作用线的距离叫做阻力臂D.力臂一定在杠杆上分析:力臂是从支点到力的作用线的距离,简单地说,就是“点到线”的距离,而不是“点”到“点”
This chapter is the beginning of the ninth grade on the volume, contains the knowledge point, the physical concept is more, we put it into simple mechanical, power and mechanical, mechanical efficiency of the three units to resolve the typical problems. First, the simple mechanical analysis of a typical example 1 on the arm, the following statement is correct () A. The distance from the power point to the fulcrum is called the power arm B. Arm is the length of the lever C. From the fulcrum to the resistance line The distance is called the resistance arm D. The arm must be analyzed on the lever: The arm is the distance from the fulcrum to the line of action of force, in short, it is the distance from “point to line ” instead of “point To ”dot "