Or, if you're a pediatrician with a really small patient who will not sit still, it's because the laws of quantum mechanics don't allow an object to have a definite position and momentum.

或者你是个儿科医生,而你的小病人却总也坐不住,这是因为量子力学,不允许物体同时具有确定的位置和动量

耶鲁公开课 - 基础物理课程节选

I think it's clear, the position of the object with respect to the ground, this vector is the same as the position of the object with respect to the plane, plus the position of the plane with respect to the ground.

我觉得很明显,物体相对于地面的位置,这个矢量等于,物体相对于平面的位置矢量,加上物体相对于地面的位置矢量

耶鲁公开课 - 基础物理课程节选