How do we know 10 Newtons is acting?

我们怎么知道是作用力是 10 牛呢
I think you people know how we can say that with confidence.

我想你们肯定都知道我们为何如此确信
How do we know the mass of this is 5 kilograms?

我们怎么知道质量就是 5 千克呢
We know how you got that from an earlier experiment.

我们通过之前的实验知道了这些
Now, we know how the numbers come in.

现在我们知道这些数字是如何得到的了
The algebra is, of course, very trivial here.

这些数字本身当然是平凡无奇
Then, the next problem is a little more interesting.

下面这道题目会更有意思
Here I got 3 kg and I got 2 kg

一个物体 3 千克另一个 2 千克
and I'm pushing with 10 Newtons and I want to know what happens.

现在我用 10 牛的力推它我想知道接下来会怎样
One way is to just use your common sense and realize

第一种方法就是你可以通过常识感觉到
that if you push it this way,

如果你这样推它
these two guys are going to move together.

这两个物体会一起运动