That doesn't happen in flight,

飞到天上之后就不这样了
but it happens during takeoff.

但起飞的时候确实会这样
That is an example of a person for whom the Law of Inertia does not work.

这就是一个惯性定律不成立的例子
This is something you guys may not have realized.

这一点你们可能没意识到
Newton's laws are not for everybody.

其实牛顿定律并不适用于所有情况
You have to be what's called an "inertial observer."

你必须是"惯性观察者"才行
If you're an inertial observer,

如果你是惯性观察者
then in your system of reference,

那么在你的参考系内
objects left at rest will remain at rest.

静止的物体会保持静止
The plane that's ready to take off or is taking off is not such a system.

但即将起飞或正在起飞的飞机并不是这种系统
The Earth seems to be a pretty good inertial system,

地球看上去是个不错的惯性系
because on the ground, you leave something,

因为什么东西放在地上