So, what's the conservation of mass if we divide by the atomic masses here?

那么质量守恒是什么呢？,如果我们在这儿按原子质量划分？

麻省理工公开课 - 固态化学导论课程节选

First one says, if you knew the force acting on any body, without going into what caused the force, then you may set that force equal the mass times acceleration of the body.

第一部分是,如果你知道作用在任一物体上的力,无论这个力的来源是什么,都可以令力等于质量乘以物体的加速度

耶鲁公开课 - 基础物理课程节选