But there's another way to do this and I'm going to give you now the simplest example of the other way, which is to draw free-body diagrams.

不过还有另外一种方法,现在我来给你们演示,另外一种方法最简单的例子,也就是隔离法的受力分析

耶鲁公开课 - 基础物理课程节选