That's how by either balancing the unknown force with a known force or by simply measuring the acceleration as I fall towards this podium and multiplying by mass, you can find the force that exerts on me.

我们既可以让未知力与已知力平衡,也可以只测量我冲向讲台时加速度的大小,再与我的质量相乘,都能求出作用在我身上的力的大小

耶鲁公开课 - 基础物理课程节选

Right. The most famous example is that when things fall near the surface of the Earth, they all have the same acceleration, and the acceleration that's common is called g, and that's 9.8 m/s^.

最有名的例子就是,当物体地球表面附近下落时,它们都拥有相同的加速度,这个普遍的加速度叫做g,大小为9.8m/s^

耶鲁公开课 - 基础物理课程节选