新课程实施以来,高考对“运用数学知识和方法解决物理问题”能力的考查力度有所加大。运用作“辅助圆”的方法,可以巧妙地分析矢量的合成、竖直平面内的匀变速直线运动、带电粒子在匀强磁场中运动等动态变化问题,从而将复杂问题简单化,抽象问题直观化。一、利用辅助圆分析力的合成问题例1如果两个力之间的夹角大于90°,现保持其夹角不变,同时增大这两个力的大小,则其合力大小可能如何改变?分析:对于此题,学生很容易按经验解答,认为两 Since the implementation of the new curriculum, college entrance examination on “use of mathematical knowledge and methods to solve physical problems,” the ability to examine the degree has increased. The method of “auxiliary circle” can be used to analyze the dynamics of the vector synthesis, the uniform linear motion in the vertical plane and the movement of the charged particles in a uniform magnetic field, so as to simplify and abstract the complex problem Visualize the problem. First, the use of auxiliary circular analysis of the composition of the problem Example 1 If the angle between the two forces is greater than 90 °, now keep its angle unchanged, while increasing the size of these two forces, the resultant force may change how the size Analysis: For this question, students are easy to answer according to experience, that two