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

This equation is telling you if you compress it, namely if x is negative, F will be then positive, because it's pushing you outwards.

这个方程告诉我们,如果压缩弹簧,即令 x 为负,F 就为正,因为推力的方向向外

耶鲁公开课 - 基础物理课程节选

It says, if you pull it to the right, so that x is positive, the spring will exert a force which is in the negative direction; that's why you have a minus sign.

就是说,如果你向右拉,x 取正值,弹簧产生的力方向为负,这就是这里用负号的原因

耶鲁公开课 - 基础物理课程节选