碰撞问题是历年各地物理高考的热点,此类考题同学们的得分率一般都较低,究其原因,则是没能够根据题目特点灵活地运用所学知识。在碰撞过程中,由于相互作用的时间很短,若将相互碰撞的物体作为一个系统来看,外力通常远小于碰撞物体之间的内力,它们的冲量可忽略,认为碰撞的过程中系统动量守恒。同时,在碰撞的过程中不可能有其他形式的能量转化为机械能,只是系统内物体间机械能相互转化,或一部分机械能转化为内能,因此系统的机械能不会增加。由于碰撞过程时间 Collision problem is all over the years physical examination hotspots, such test questions the students generally have lower scoring rates, the reason, it is not based on the characteristics of the subject can be flexibly applied knowledge. In the collision process, due to the interaction of a very short time, if the collision of objects as a system point of view, the external force is usually much smaller than the impact of internal forces between objects, their impulse negligible, that the collision process of conservation of momentum . At the same time, it is impossible for any other energy to be converted to mechanical energy during the collision, only the mechanical energy among the objects in the system can be transformed into each other, or a part of the mechanical energy can be converted into the internal energy. Therefore, the mechanical energy of the system can not increase. Due to the collision process time