So the Earth is an inertial frame of reference, if you go in a train relative to the Earth at constant velocity, you're also inertial.

所以,地球是一个惯性参考系,如果你坐在相对于地球匀速运动的火车里,你也处于惯性状态

耶鲁公开课 - 基础物理课程节选

Second formula tries to relate the final velocity of some time, t, to the initial velocity and the distance traveled with no reference to time.

第二个式子能把某段时间t的末速度,和初速度,经过的路程联系在一起,并且不引入时间

耶鲁公开课 - 基础物理课程节选