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

是个物理学家的玩具可以演示角动还有动能和势能。

As it did, angular momentum became important.

随着它的坍缩，角动变得重要起来。

That's called conservation of angular momentum.

「角动守恒定律」。

But the original star's angular momentum is preserved.

但原始恒星的角动被保留了下来。

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

最酷的是它可以永久性地保持角动。

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

由于角动不变，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.

更多的角动意味着 她可转更多圈 ──在因摩擦力损失动，补充之前。

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

以子涡旋例，它基本上是超导体和超流体等材料中角动的漩涡，使它们具有奇特的性质。

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

除了摩擦损耗的动之外，当舞者踮起脚尖时 角动必须保持不变。

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，它可能不会保持恒定的速度，但它的角动会保持不变。

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，它们可以在不改变其净角动的情况下摆动。

That's called the conservation of angular momentum.

- 就是所谓的角动守恒。

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

是因角动守恒的原理。

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

基本上， 物体的角动描述了它保持旋转的趋势。

So the approach we chose to use is angular momentum.

所以我们选择使用的方法是角动。

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

和线性动、角动一样 一直得救。

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

你不能创造或破坏角动。 它总是必须去某个地方。

Some examples of vectors are displacement, velocity, acceleration, force, momentum, torque, angular momentum, and those are all vectors.

向的一些例子是位移、速度、加速度、力、动、扭矩、角动, 些都是向。

In physics, angular momentum describes something’s tendency to stay rotating once it’s started.

在物理学中， 角动描述了某物一旦开始就保持旋转的趋势。

And that factor is angular momentum.

斜率，那个因素就是角动。