if you're talking about the chalk--if I throw the chalk,

这支粉笔如果我扔出这支粉笔
you will have to know where it is and how fast it's moving.

你就想知道它的位置和速度
Dynamics then tells you why the object goes up,

而动力学则会告诉你为什么物体向上运动
why the object goes down and why is it pulled down and so on.

为什么向下运动为什么停下来等等
That's dynamics.

这就是动力学
The reason it comes down is gravity is pulling it.

物体向下运动是因为重力作用
In kinematics,

在运动学中
you don't ask the reason behind anything.

我们不关心现象背后的原因
You simply want to describe things the way they are

你只是单纯描述物体的实际状态
and then dynamics tells you how they changed and why they changed.

而动力学则是解释它们运动的方式和原因的
So, I'm going to illustrate the idea of kinematics

所以我会用很简单的例子
by taking the simplest possible example.

来解释运动学