We will deal with that today, and we call that an elastic collision.
我们今天要处理这情况，我们称它为弹性碰撞。
I will often call it a completely elastic collision, which is really not necessary.
我常叫它完全弹性碰撞，但其实并不需要这样叫。
If you want to call it the collision, but there was kinetic energy afterwards.
你若称之为碰撞，但之后又有了动能。
If you want to call it the collision, but there was kinetic energy afterwards.
你若称之为碰撞，但之后又有了动能。
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