Park Service rangers explain that mother bats find their babies by remembering their location, their smell and the sound of their cry.

VOA: special.2009.12.07

If I gave you the location of a particle as a function of time, you can find the velocity by taking derivatives.

如果我给出物体的位移是时间的函数,你可以通过求导来得到速度

耶鲁公开课 - 基础物理课程节选