物理学 第五版 2-1牛顿定律 ★牛顿定律的研究对象是单个物体(质点) The research subjects of Newton's law is single objects Mass point) ★瞬时关系( nstantaneous relationship ★矢量关系( ector relationsh) ☆力的叠加原理( The principle of superposition of force) F=∑F物体所受合外力mh he total external force acting on the object F=F1+F2+F3+ a,+ 2 a2+ 第二章牛顿定律 6/16第二章 牛顿定律 物理学 第五版 2-1 牛顿定律 6/16 瞬时关系(Instantaneous relationship ) 牛顿定律的研究对象是单个物体（质点） 矢量关系(Vector relationship ) The research subjects of Newton’s law is single objects (Mass point) 力的叠加原理(The principle of superposition of force) F   Fi   物体所受合外力 The total external force acting on the object. 1 2 3 F  F  F  F  ...     1 2 3 a  a  a  a  ...    