摘要
对质点系在某一时间间隔内所受外力的主矢为零的情况下，建立了关系式用该关系式代替质心运动守恒定律可以更方便地解决有关力学问题．
Under the condition that the principal vector of the external force on a particle system at certain time interval equals zero, the relation =0 is formed, which may be used instead of tradition barycentric movement conservation law to solve relevant mechanical problems easily.
