物体在做圆周运动或圆周运动的一部分运动时,受到的合力或部分合力指向圆心,这就是向心力.向心力是效果力,在受力分析时不单独分析出来,它由物体受到的其他力的合力或几个力的分力来充当.在解决此类问题时,关键是要对物体进行受力分析,找出物体做圆周运动的所在平面及圆心,以便找出向心力的来源,再根据动力学列方程式求解.教材上列举了两类圆周运动的实例,现我们由此两类问题展开延伸,以达到对知识的融会贯通.一、汽车过桥问题 When an object moves in a circular motion or a circular motion, the resulting resultant force or partial resultant force points to the center of the circle, which is the centripetal force, which is the force of force that is not separately analyzed when subjected to force analysis and the resultant force of the other forces it receives from the object Or a few force components to play in solving such problems, the key is to force analysis of objects to find the object to do the circular motion of the plane and the center of the circle in order to find the source of centripetal force, and then based on the dynamics Column equations to solve the textbook listed two examples of circular motion, now we extend the two types of problems, in order to achieve the mastery of knowledge through.