竖直平面内的圆周运动是典型的变速运动,高中阶段只分析通过最高点和最低点的情况,经常考查临界状态,其问题可分为以下两种模型.一、两种模型模型1:“轻绳类”绳对小球只能产生沿绳收缩方向的拉力(圆圈轨道问题可归结为轻绳类),即只能沿某一个方向给物体力的作用,如图1、图2所示,没有物体支撑的小球,在竖直平面做圆周运动过最高点的情况:(1)临界条件:在最高点,绳子(或圆圈轨道)对小 The circular motion in the vertical plane is a typical variable speed motion, the high school phase only analyzes the situation that passes the highest point and the lowest point, and often examines the critical state. The problems can be divided into the following two models: First, two models Model 1: The “light rope class” rope can produce only a pulling force along the rope contraction direction (circle orbit problem can be attributed to the light rope class), which can only force the object in one direction, as shown in Figure 1 and Figure 2 As shown in the figure, there is no object supporting the ball, in the vertical plane circular motion over the highest point of the case: (1) critical conditions: at the highest point, the rope (or circle orbit)