因此，可以通过密度求一个平面物体的质量。

So, you can get the mass of a flat object with density.

youdao

这些物体的质量是？，我已经略为提及？

And now comes a part, what are the masses of these objects?

youdao

也可以这么说，“它和物体的质量，成正比。”

And we could have said, "Yeah, it's probably proportional to the mass somehow."

youdao

Therefore, when you divide by the mass to get the acceleration, the response of different bodies is inverse to the mass.

因此,当你拿力除以质量得到加速度时,不同物体的加速度与质量成反比

耶鲁公开课 - 基础物理课程节选

We know now with the same spring, by this comparison, we will find all objects now can be attributed a mass.

我们现在知道利用相同的弹簧,采用这种比较的方法,就会发现,所有物体都有确定的质量

耶鲁公开课 - 基础物理课程节选

But gravity has a remarkable property that the pull of the Earth is itself proportional to the inertia of the object.

重力有一个显著特征,即地球的引力,与物体的质量成比例

耶鲁公开课 - 基础物理课程节选