Momentum is conserved, and that's called the conservation of momentum.

动量守恒，这就叫作动量守恒。

youdao

And so now I can apply, for the first time, the conservation of momentum.

我可以第一次应用，动量守恒。

youdao

So the conservation of momentum tells you what the speed is after the collision.

动量守恒定律告诉你,碰撞后速度是多少。

youdao

This is because of conservation of angular momentum, the same property that causes ice skaters to spin faster if they draw their arms in.

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