竖直平面内的圆周运动和机械能守恒定律是高考的重点内容,是考查学生分析综合能力的基础.[1]竞赛题和高考题常会以相同的模型出现,[2]这与高考物理改革的深化是一致的,本文通过对一道竞赛题的拓展及变式分析,以便学生更加系统地掌握相关知识.原题.(第29届全国中学生物理竞赛预赛第11题)如图1所示,一根跨越 The circular motion in the vertical plane and the law of conservation of mechanical energy are the key contents of the college entrance examination and are the basis for examining students’ comprehensive ability. [1] Contest questions and college entrance examination questions often appear in the same model [2] Deepen is the same, this article through the expansion of a competition and variant analysis, in order to enable students to more systematically grasp the relevant knowledge.Autumn. (29th National Junior High School Physics Contest 11 questions) as shown in Figure 1, a Spanning roots