You simply want to describe things the way they are and then dynamics tells you how they changed and why they changed.

你只是单纯描述物体的实际状态,而动力学则是解释它们运动的方式和原因的

耶鲁公开课 - 基础物理课程节选

Dynamics then tells you why the object goes up, why the object goes down and why is it pulled down and so on.

而动力学则会告诉你为什么物体向上运动,为什么向下运动,为什么停下来,等等

耶鲁公开课 - 基础物理课程节选