Clearly the heavier the atom the less affective it is because it's sort of like a billiard ball collision with a heavier atom.

很明显，原子越重，它就越有效，因为那有点像有一个重一点的原子，的撞球的撞击。

youdao

Look at the billiard ball alone — - forget the ping-pong ball — and try to see that the speed of the billiard ball is practically unaffected by the collision.

我们只看台球-，完全忽略乒乓球-，来看看台球的速度，它实际未受碰撞影响。

youdao