As it did, angular momentum became important.

随着坍缩，角动量变得重要起来。

That's called conservation of angular momentum.

这称为「角动量守恒定律」。

But the original star's angular momentum is preserved.

但原始恒星角动量被保留了下来。

What's neat is that they can maintain angular momentum indefinitely.

最酷可以永久性地保持角动量。

It's a physics toy that demonstrates angular momentum, potential energy, and kinetic energy.

个物理学家玩具可以演示角动量还有动能和势能。

Since the angular momentum doesn't change, when the distance increases the velocity has to decrease.

由于角动量不变，当距离增加时，速度就会减小。

More angular momentum means she can make more turns before needing to replenish what was lost to friction.

更多角动量意味着 她可转更多圈 ──在因摩失动量，需再补充之前。

Take quantum vortices, which are basically whirlpools of angular momentum in materials like superconductors and superfluids, giving them strange properties.

以量子涡旋为例，基本上超导体和超流体等材料中角动量漩涡，使们具有奇特性质。

And except for what's lost to friction, that angular momentum has to stay constant while the dancer is on pointe.

除了摩耗动量之外，当舞者踮起脚尖时 角动量必须保持不变。

Well, as a planet orbits the Sun it may not keep a constant speed but it does maintain its angular momentum.

当行星绕太阳运行时，可能不会保持恒定速度，但角动量会保持不变。

That's called the conservation of angular momentum.

- 这就所谓角动量守恒。

Because angular momentum must be conserved.

因为角动量必须守恒。

So the approach we chose to use is angular momentum.

所以我们选择使用方法角动量。

This is because of a principle called conservation of angular momentum.

这因为称为角动量守恒原理。

Basically, an object’s angular momentum describes its tendency to stay rotating.

基本上， 物体角动量描述了保持旋转趋势。

And, like linear momentum, angular momentum is always conserved.

和线性动量、角动量一样 一直得救。

By bending in the middle and using fast twitch muscle fibers, they can whip around without ever changing their net angular momentum.

透过在身体中断弯曲并使用快肌纤维，们可以在不改变其净角动量情况下摆动。

And that factor is angular momentum.

斜率，那个因素就角动量。

You can't create or destroy angular momentum. It always has to go somewhere.

你不能创造或破坏角动量。 总必须去某个地方。

This is because they have angular momentum and resist having it changed, according to Newton's first law.

这因为根据牛顿第一定律，们具有角动量，并抵抗其改变。