注意，这里，重力势能是增加的。
注意，重力势能，是减小的。
我先给你一个对于，重力势能的形式定义。
Let me first give you the formal definition of gravitational potential energy.
所以你在利用，重力势能，转换成，动能。
So you're using, then, the conversion of gravitational potential energy to kinetic energy.
你们看，是重力势能。
我们把mgy叫做。,给它一个名字，重力势能
We call mgy... we give that a name, "gravitational potential energy."
重力势能的关系。
这是重力势能。
那么它将是,正的重力势能，这样的话这点,就比另一点高。
Then this will have a positive gravitational potential energy, and this will have one that is higher than this one by this amount.
重力势能，这样增长,重力;,是在这个方向,当我在这里。
When I'm here, gravitational potential energy ; increases in this way; the gravitational force is in this direction.
可以在车内装个圆盘，可以称之为飞轮，可以转化，重力势能。
You can install a disk in your car, which I would call, then, a flywheel, And you can convert the gravitational potential energy.
现在要做的，就是要转化，所有这些重力势能，变成圆盘的动能。
Now, what we would like to do is we would like to convert all this gravitational potential energy into kinetic energy of that disk.
这就是重力势能，转换到，动能，再回到，重力势能，最终停在这里。
There is a conversion from gravitational potential energy to kinetic energy back to gravitational potential energy, and it will come to a stop here.
因此如果我画一张,重力势能,受y变化的图，那么会得到一条直线。
So if I make a plot of the gravitational potential energy as a function of y, then I would get a straight line.
因此，该物块的重力势能的减少，等于该弹簧的弹性势能的增加。
Hence, the loss of gravitational potential energy of the block equals the gain of elastic potential energy of the spring.
不管你是乘电梯，去大厦的顶层，或者是步行，重力势能的变化是相同的。
Whether you take the elevator to the top of the Hancock Tower or whether you walk up the stairs, the change in gravitational potential is identical.
所以减速，刹车通过，能量的转换达到了，从，重力势能，转化到旋转圆盘上。
So the slowdown, the "braking" is now done because of a conversion from your linear speed which comes from gravitational potential energy to the rotation of the disk.
气流筛分机摈弃重力势能作业原理，采用空气作载体，动能作功的作业原理。
Working principles Airflow screen machine abandon gravitational potential energy principle of operation, using air as the carrier, kinetic energy of the operation principle of work.
形式定义就是,它在点P的重力势能,等于我，将物体从无穷远处,移动至点P所做的功。
The formal definition is that the gravitational potential energy at a point P is the work that I, Walter Lewin, have to do to bring that mass from infinity to that point P.
重要的是，如果我们得到了重力，势能的正确值，当我们远离这个物体，重力势能就会，增加。
What is important, of course, if we get the right answer for the gravitational potential energy, that when we move away from this object that the gravitational potential energy increases.
当地球内部在重力势能和放射能的作用下继续熔融时，地球表面固化为原始岩石圈。
With effect of geopotential and radiation energy, when the interior of the earth continued to melt, the surface of the earth solidified to form the original lithosphere.
好了，我的目标是，用通常的方式，为你们评价重力势能，不是用一个特殊的，接近地球的案例。
Okay, my goal was to evaluate for you the gravitational potential energy the way that it is defined in general, not in a special case when we are near the Earth.
对于走路你可能很抓狂，但你一旦到了顶层,你就是在第60层,你的重力势能,与你如何到达那里无关。
You might be winded doing it the second way, but when you get to the top and you are at the 60th story your gravitational potential is independent of how you got there.
如果看这个结果-，重力势能与动能之和，在重力作用下，是守恒的-，马上，很明显的发现，动能为0的地方。
If I look at this result — the sum of gravitational potential energy and kinetic energy is conserved - for gravitational force — then it is immediately obvious where we put the zero of kinetic energy.
石漠化形成的主要原动力是自然生态系统的雨水动能和重力势能，亦是其形成的直接动力或第一性动力。
Rain energy and gravitational potential energy were original energies of rocky desertification form in nature ecosystem, and were direct or primary motivity.
石漠化形成的主要原动力是自然生态系统的雨水动能和重力势能，亦是其形成的直接动力或第一性动力。
Rain energy and gravitational potential energy were original energies of rocky desertification form in nature ecosystem, and were direct or primary motivity.
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