There's the hard sphere. It wants to collide against the wall to create a force on the wall, and I have a couple of the hard spheres that are nearby, right, and in the absence of any interactions, I get a certain pressure.

给墙一个作用力,现在它的附近，还有许多小球,没有相互作用时,它将直接冲向这面墙。

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Maybe we could leave this wall white and paint the other wall red.

也许我们可以把这面墙留白，把另一面墙刷成红色。

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