杠杆的平衡条件是分析和解决杠杆问题的重要切入点,应用时关键在于紧扣影响杠杆平衡的四个要素:动力、动力臂、阻力、阻力臂,分析它们在具体问题中的大小,搞清它们的变化情况,从而结合杠杆的平衡条件,进行综合分析、推理、计算.现以一种常见题目的多种变换为例加以说明.原形题: The balance condition of leverage is an important entry point to analyze and solve the problem of leverage. The key to application lies in closely relating the four factors that affect leverage balance: power, power arm, resistance, and resistance arm. Analyze their size in specific issues and find out Their changes, combined with the balance conditions of the levers, perform comprehensive analysis, reasoning, and calculations. Now a variety of transformations of a common topic are taken as examples for illustration.