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

It's not talking about the gravitational pull of the Earth on an object.

没提到地球对物体的引力

耶鲁公开课 - 基础物理课程节选

You cannot tell the mass, because what you are doing now is appealing to the notion of mass as something that's related to the pull of the Earth on the object.

你无法测出质量,因为你现在所做的是把质量,用地球对物体的引力给替代了

耶鲁公开课 - 基础物理课程节选

For example, we know that if a body is near the surface of the Earth, the force of gravity of that object seems to be m times g, where g is 9.8.

例如,我们知道,如果在地球表面有一个物体,该物体受到的重力大小为 m 与 g 的乘积,g 等于 9.8

耶鲁公开课 - 基础物理课程节选