因此，我们可以说，该系统有内势能。
We can therefore say that the system has internal potential energy.
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.
所以现在系统内,总能量是多少-,是动能和,势能之和吗？
So what, now, is then the total -- energy of the system-- that is, the sum of the kinetic energy plus the potential energy?
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