该人造卫星每100分钟绕地球旋转一圈。
The satellite revolves around the earth once every hundred minutes.
这些镜子可以在几千英里的高空以地球绕地轴旋转的速度运行。
The mirrors could orbit—thousands of miles high—at the same speed as the earth turns on its axis.
它们通过质量绕轴旋转机械存储能量。
They store the energy mechanically by rotating mass around an axis.
然后去测量,绕该轴旋转物体的困难程度。
Then you would try to measure how hard it is to spin your object around that axis.
还是看个例子吧，有一张均匀的唱盘，让它绕中心旋转有多难呢？
Let's do an example. Let's try to figure out if we have just a uniform disk how hard it is to spin it around its center.
这是圆盘，我们刚讨论过,绕质心旋转。
So this is a disk, and we just discussed the rotation about the center of mass.
比如，试着让一张纸绕其中心轴旋转，看看有多困难。
For example, you can try to measure how hard it is to spin this sheet of paper about an axis that is in the center of it.
那一个三维的球来说，无论你怎样把它绕中心旋转，它都会保持不变。
You take a sphere, in 3 dimensions, you rotate around the center of the sphere, and all those rotations leave the sphere alone.
也就是绕x轴旋转。
所以如果你旋转它3次,放开它，它会转3次回来，然后会达到平衡,在停止之前,会绕三次。
So if you rotate it three times and then let it go, it goes first three times back, then it's at equilibrium, and then it winds three times up again before it stops.
近地半球总是面对地球，远地半球总是远离地球，因为月球在绕地球旋转的同时，它也在以同样的速率绕自己的轴自转。
The near side is always facing Earth and the far side is always facing away, because the moon revolves around the Earth at the same rate that it rotates on its own axis.
地球自转，明显地倾斜于太阳，而月球不同，它几乎笔直地绕太阳旋转。
Unlike Earth, which rotates on a significant tilt to the Sun, the Moon is barely tilted at all.
角动量的大小，取决于旋转中的滑冰选手的旋转速度、体重和绕旋转中心的质量分布。
The amount of angular momentum, say, a spinning skater has depends on both the speed of rotation, and the weight and distribution of mass around the center.
地球绕一个贯穿南极点和北极点的假想轴旋转，这个假想轴称为地轴。同时也绕太阳公转。
The Earth spins on an imaginary line called an axis that runs from the north pole to the south pole, while also orbiting the sun.
由于地球自转速率发生偏离，因此当把地球绕中轴旋转一圈作为一个单位时，（这种偏离）就相当于一秒钟时间。
Since Earth’s rotation rate varies, so would the value of one second when it’s defined as a fraction of the time it takes for one spin of the Earth on its axis.
它并不只是简单地绕原子核旋转，而是同时进行公转和自旋。
It doesn't simply orbit the nucleus, but as it orbits it spins.
第三颗被称作比邻星的红矮星，在相当远的距离之外绕这两颗恒星旋转，由于亮度太弱费希尔的团队无法对其进行研究，不过它也可能拥有质量较小的行星。
The third star, a red dwarf called Proxima Centauri, circles this couple at a considerable distance and is too faint for Fischer's team to study, but it could boast small planets, too.
而且，连接到空间站的航天飞机做了非常精彩的“表演”，它缓慢的绕轨道旋转着。
And the linked station-shuttle did what any good fashion model does. It slowly turned and pivoted on its orbital runway.
在航行的最初，新视野号的工程师们将与时间赛跑：为了从木星获得引力推进力，飞船将花三年时间绕木星旋转。
Initially, the New Horizons engineers were also racing against the clock: By getting a gravity kick from Jupiter, the spacecraft could shave three years off its total mission time.
毋庸置疑，是太阳拉着行星绕其旋转。
这是一个绕原点逆时针旋转的向量场。
It's a vector field that just rotates around the origin counterclockwise.
但它完全不同，转动惯量，如果将其绕这轴旋转。
But it's completely different, the moment of inertia, if you rotated it about this axis.
一个飞盘是有边缘，所以可以，让它绕着边缘上某点旋转，就像这样，绕边缘点转动它。
A Frisbee has this rim so you can actually try to make it rotate around the point on the circumference by holding it near the rim and spinning it there.
特别地，绕平面上一点旋转物体，同样可以想象，旋转一个实体。
In particular, we have been rotating things about just a point in the plane What you could imagine also is instead you have your solid.
它是绕垂直轴旋转的。
我迫使这个物体，绕这轴旋转。
And I'm going to force this object to rotate about that axis.
举个例子来说，把一个圆绕中心旋转，你会发现它保持不变。
A circle, for example, is symmetric under rotations around the center of the circle. You rotate around the center of the circle, the circle remains unchanged.
然后我将使其绕轴旋转-,像这样旋转-,为角速度,这个距离记为。
Now I'm going to rotate this about this axis-- - it's going around like this-- with an angular velocity omega R and this is at a distance, R.
然后我将使其绕轴旋转-,像这样旋转-,为角速度,这个距离记为。
Now I'm going to rotate this about this axis-- - it's going around like this-- with an angular velocity omega R and this is at a distance, R.
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