Where is the center of mass of this system?
这系统的重心何在？
And the center of mass of this eraser is somewhere in the middle.
这个橡皮重心在中间的某一点。
So here is the center of mass of that ladder, right in the middle.
这里是梯子的重心，在正中央。
We want to know what the velocity is of the center of mass of the other one.
我们想知道，质量重心的速度是多少，对于另一个。
But one that you might have seen in physics, we care about maybe where is the center of mass of a given object?
但你们可能也在物理学中见过了，就是求一个给定物体的重心？
And, now, I think I know just by looking at the picture where the center of mass of this circle will be, right?
这样的话靠观察这张图片,圆的中心在哪就可以知道？
As another example the center of mass of the earth and moon moves in an approximately circular orbit around the sun.
作为另一个例子，地球和月亮的质心就是在一个绕太阳的近似的圆轨道上运行。
Measure throwing velocity from the center of mass of where the user feels the center of mass is — i. e. , the controller.
测量用户感觉的质心位置的质心投掷速度——也就是控制器。
Ten kilograms is ten meters below the rope, so clearly the center of mass of the system as a whole will be below the rope.
绳子下方10米10公斤，所以很明显，重心，将会在绳子下方。
The King's Chamber is not the center of mass of the Great Pyramid, rather it is where the primary energetic vortex is centered.
国王的墓室并不是大金字塔的质量中心，而是最初的能量漩涡的中心。
Geocenter motion is the relative displacement from the center of mass of Earth to the origin of the Terrestrial Reference Frame.
地球质心(简称地心)是指包括海洋大气等的整个地球的质量中心，地心运动是地球质量中心相对于地球参考框架原点的位移。
The center of mass of a system is defined as follows: I have here some kind of an object not just a point mass, but it has a finite size.
系统的重心,是这样定义的：,我有一个物体,不是有棱角的物体，但它大小有限。
The way you bridge the physical weight to the virtual is to use the center of mass of the physical controller to determine in-game velocity.
将物理重量桥接到虚拟对象上是通过物理控制器的重心来确定游戏中的速度的。
If you have a problem asking you to find the center of mass of something and you have no information about the density, assume it is uniform.
如果一个问题，需要知道某物的重心，而又不知道其密度，就可以假设它是个常数。
When you pick up a virtual object, the center of mass of that object and the center of mass you feel in your hand have some real separation.
当你拾起一个虚拟的物体，物体的质心和质心在手上的感觉有些分离。
Because when you stick your leg out in front of you, you actually decelerate, from the time it takes the center of mass of your body to get over your foot.
因为当你在将腿伸出到前方时，从你身体重心要赶上双脚所花费的时间来看，你其实是在减慢速度。
For side or front thrusters, use 2 to 4 thrusters per side (not set in stone), remember to place them more or less symmetrically compared to the center of mass of the ship.
对于侧推进器或前推进器，每边使用2- 4个推进器(可以改变)，记住：放置位置尽量与飞船质心相对称。
These calculations also help scientists determine the mass of black holes, which lie at the center of nearly all galaxies.
这些计算也可以帮助科学家们确定几乎所有星系中心的黑洞质量。
And I had no idea that Dafen's artist colony - the world's leading center for mass-produced artwork and knockoffs of masterpieces - had been devastated by the bursting of the U.S. housing bubble.
我也没有想到，美国房市泡沫的破裂会让这个美术家聚集地——大芬村是全球最重要的工艺品和名作仿制品批量生产基地——遭遇灭顶之灾。
The velocity of the center of mass has not changed as seen from your frame of reference, because the velocity of center of mass is always the same, remember, because momentum is conserved.
质量重心的速度，并没有发生改变，你在参照系中可以看出，因为质量重心的速度，总是保持不变，要记住，由于动量守恒。
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.
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。
But the basic idea is, then, that the center of mass will always in stable configuration line itself up below the point of suspension.
但是基本概念是，物体的重心将一直，处于稳定的结构线上，在悬挂点下面。
If I throw up a hammer, then the center of mass and only the center of mass will just go along a perfect parabola as if it were just a tennis ball.
我若是抛铁锤，那么质量重心，也是唯一的质量重心，会沿完美抛物线运动，就像一颗网球。
And ultraviolet light will interact with that little ball, the center of mass, and when I then make it dark, you will only see the motion of the center of mass.
这紫外线光可以，与小球互动，也就是质量重心，当周围暗下来，能看到质量重心运动。
In particular, we have seen the notion of center of mass.
特别地，我们学过质心的概念。
And this, now, is the position vector of the center of mass.
现在，这里是，物体的矢量中心。
So to get into the center-of-mass frame, you must subtract the velocity of the center of mass from the initial velocities.
要进入重心体系，你就必须减去速度，重心的速度，从原始速度中减去。
And now comes another unique property of the center of mass.
它还有一个特性，质量重心的特性。
How do we calculate the velocity of the center of mass?
我们怎样计算，重心速度呢？
So the center of mass will always find itself below the point of suspension.
所以物体的重心，经常处于悬挂点之下。
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