We have no other choice but to go forward and to keep our minds on acting firmly on the knowledge we already have;

VOA: standard.2010.05.17

The stuff that people tend to add sometimes is to keep drawing the 10 Newtons that's acting on that.

有人经常凭空添加的力,总是把这个 10 牛的力硬加在这个物体上

耶鲁公开课 - 基础物理课程节选