牛顿第一定律的实质、地位和作用

文章研究了牛顿第一定律的实质及在牛顿三个定律中的地位和作用。澄清了对牛顿第一定律的一些模糊认识，对认识牛顿三定律之间的关系和理论的完备性和逻辑性提出了不同的看法。文章指出：牛顿第一定律的实质是给出了一个不受力或所受合力为零，不存在加速度的系统，即通常所说的惯性系而不是力的定义，而牛顿第二、第三定律只对惯性系才成立。惯性系也不能用牛顿定律成立与否来定义。

Essence, position and effect of Newton's First Law

The essence of Newton's First Law and the position in the Newtion's three law was studied. The obscure understanding on Newton's First law was cleared up. Some different idea about the relation of Newtion's three law and the theory's completeness and logic was put forward. The essence of Newton's First Law is to give a system which is not subjected to force or the resultant of forces is zero or has no acceleration. That is normal called inertia system and not the difination of force. The Newton's First and second Law only hold to inertia system.