Galileo and Descartes replaced that with the idea of inertia.
伽利略和笛卡尔用惯性的概念将其取代。
So it is bMg divided by the moment of inertia about that point P.
也就是bMg除以,点P的转动惯量。
The car would move faster and faster down the hill because of inertia.
车子下山时会因为惯性而越来越快。
What is the moment of inertia for rotation of a rod about this axis?
关于这个轴的,旋转动动量是多少？
I have four objects here, and they all have different moments of inertia.
我这里有四个物体，它们的转动惯量也不同。
Severe losses can shock any investor out of inertia, often in destructive ways.
不过，惨痛的损失可以给投资者以震撼，让他们脱离这种惯性状态，而且这种外力通常是具备较强的破坏性的。
OK, so moment of inertia about the z axis so, what's the distance to the z axis?
关于绕z轴的转动惯量,到z轴的距离是多少？
For the moment of inertia, we want the square of a distance to the axis of rotation.
至于转动惯量，要求的其实是到旋转轴距离的平方。
Needless to say, that the moment of inertia depends on what kind of object you have.
不用说，转动惯量取决于，你选择的物体。
How hard it is to spin something, on the other hand, is given by its moment of inertia.
旋转东西有多难，换着来讲的话，是跟转动惯量有关的。
It was Galileo who expressed what he called the law of inertia and I will read you his law.
伽利略在当时，提出惯性定律，他的观点是这样的。
But it's completely different, the moment of inertia, if you rotated it about this axis.
但它完全不同，转动惯量，如果将其绕这轴旋转。
If I know the moment of inertia, then I know how much rotational kinetic energy there is.
若知道转动惯量我就能知道，转动动能是多少。
By being still, you lose momentum, and the level of inertia of our current position increases.
就像如果你处于静止状态，你就会失去动量，你处于静止状态的惯性就会增加。
Populations can rise while fertility declines because of inertia, which matters a lot in demography.
根据人口统计学，生育率降低时人口因为惯性仍然会增长。
It has to do, of course, with the moment of inertia, but again, it's independent of mass, radius and length.
肯定是，与时间惯量有关，再次，它与材料无关，还有半径和长度无关。
Your present state of inertia is inherent in this type of condition, and you're in a very serious state.
你现在的懒惰状态是这种情况所固有的，你的情况很严重。
We have the mass of the sun, we have the radius of the sun so you can calculate the moment of inertia of the sun.
我们知道太阳的质量，太阳的半径,所以可以计算出,太阳的惯性是多少。
I will ask you for a moment of inertia for some weird line or something like that. OK, but these you should know.
我会让你们求一些，比较奇怪的曲线的转动惯量，这些你们都应该知道。
Audience: But memories are non-existent, they are in a state of inertia, unless somebody is there to remember.
听众：但是记忆是不存在的，记忆处于不活动的状态，除非有人回忆起来。
In rotation, force becomes torque, mass becomes moment of inertia, and acceleration becomes angular acceleration.
在旋转时，力变成力矩，质量变成转动惯量，加速度变成角加速度。
For example, the moment of inertia about the z-axis is dV the triple integral of x squared plus y squared density dV.
例如，关于z轴的转动惯量,是∫∫∫δ
Call it "smart panic" — calculated actions that free you from the chains of inertia without compelling you to go haywire.
我们将其成为“明智的恐慌”- - - - - -这种方式可以使得你脱离惯性，但也不会使你陷入紊乱。
I mean, there are some spokes here, but let's assume that everything is here, so then the moment of inertia is MR squared.
我是说，有一些偏差，但是假设每件事都在这，所以时间惯量是MR的平方。
And so I know now I can substitute that in there rMg so I get an omega precession now equals rMg times the moment of inertia.
我知道我可以替换,得到ω等于,乘以时间惯量。
Torque divided by moment of inertia is what will cause the angular acceleration, namely the derivative of angular velocity.
扭矩除以转动惯量,就会引起角加速度，也就是角速度的导数。
So we now have a way of calculating the kinetic energy of rotation provided that we know how to calculate the moment of inertia.
现在我们有一个计算，旋转动能的方法，如果我们知道，怎样计算转动惯量。
So we now have a way of calculating the kinetic energy of rotation provided that we know how to calculate the moment of inertia.
现在我们有一个计算，旋转动能的方法，如果我们知道，怎样计算转动惯量。
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