In the but-tocks, sir. Well, that must be a sight.

VOA: standard.other

Mathematically, it's done by taking the expression for R and differentiating everything in sight that can be differentiated as vector t.

从数学上看是这样的,写出 R 的表达式,并对所有可以进行矢量微分的部分,对时间 t 求微商

耶鲁公开课 - 基础物理课程节选

Mathematically, it's done by taking the expression for R and differentiating everything in sight that can be differentiated as vector t.

从数学上看是这样的,写出 R 的表达式,并对所有可以进行矢量微分的部分,对时间 t 求微商

耶鲁公开课 - 基础物理课程节选