注意,这里,重力势能是增加的。
那么什么是势能,答案不是一定的。
总功指的是势能,和动能的总和。
这是点c的势能,在此达到最大值。
对于自由电子,因此没有什么势能。
It is a free electron so there is no potential energy to be accounted for.
引力能就是电势能,库伦电势。
The attractive energy is just the potential energy, Coulombic potential.
势能差的单位是什么,伏特。
在这个例子中,自发变化减小了势能。
The spontaneous change lowers the potential energy in that case.
注意,重力势能,是减小的。
动能和势能,总和没有改变。
The sum of kinetic energy and potential energy doesn't change.
事实上,它会,朝着低势能方向移动。
In fact, what will happen is it will go to a lower potential energy.
势能减小的方向,如果我们知道这个力。
因此这是动能,这是势能。
So this is the kinetic energy and this is the potential energy.
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.
所以动能增加,势能不变,所以总能量增加。
So the kinetic energy has increased; the potential energy is the same, so the total energy is up.
在物理学里面,把势,称为势能。
In physics, you call potential, electrical potential or gravitational potential, the potential energy.
你们看,这是,我们已经得到的,势能的等式。
You see, that is the term of the potential energy that you have there.
正确的姿势能使胸腔低处更好地扩展。
Good posture allows for greater expansion of the lower rib cage.
但问题在于——这样的趋势能持续多久?
但这种良性趋势能否持续还是一个问号。
重力势能的关系。
这是在轨道内这个,半径的物体的动能,这是势能。
This is the kinetic energy for something in orbit at this radius, and this is the potential energy.
这是重力势能。
动能为,势能为U,所以这是。,这是。
Well, the kinetic energy is minus energy is U, and so this is... +1/2U this is plus one-half U.
,势能是多少。
那么势能呢?
现在是势能。
我们知道,机械能守恒定律-,动能和,势能的总和。
Then we have the conservation - of mechanical energy — the sum of kinetic energy and potential energy.
我们知道,机械能守恒定律-,动能和,势能的总和。
Then we have the conservation - of mechanical energy — the sum of kinetic energy and potential energy.
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