I'm glad to hear that no one counted this r equal zero as a node.

我很高兴没听到有人把ｒ等于０这处也算作是一个节点。

麻省理工公开课 - 化学原理课程节选

At infinity, there's no stored potential energy, and it drops off more and more negative as one over R.

在无限远处，没有储存的势能，并且它向负方向减少，当距离超过R时。

麻省理工公开课 - 固态化学导论课程节选

If it's going in a circle, you will say from now on, that it, indeed, has an acceleration, even though no one's stepping on the accelerator, of amount v^2 over R.

如果它在一个圆周上运动,你会说从现在起它其实有加速度,即使没有人去踩油门,加速度大小为 v^2 / R

耶鲁公开课 - 基础物理课程节选