来自《耶鲁大学开放课程：基础物理 第7集 第7集》
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If the total energy is positive,如果总能量是正值 -
it can go to infinity.那么它就会跑到无穷远处 -
And zero is the borderline case.零就是这两种情况的界限 -
So, why is it that if the total energy is negative,那么为什么总能量为负时 -
the body can never run off to infinity?物体就无法跑开到无穷远处呢 -
Can anyone think of a contradiction you would have,有人能与出反面例子吗 -
if a body of negative energy found itself at infinity?比如一个在无穷远处带负能量的物体 -
Yes?请讲 -
No, at infinity the potential energy is zero.不对 在无穷远点上势能是零 -
What about kinetic energy?那动能呢 -
Some positive number, right?应该是正值 对吗 -
But its initial energy was negative,但它的初始能量是负的