Acceleration is speed divided by time again, so meters per second per second.

加速度是速度再除以时间，即每秒米每秒。

Accelerating at an initial rate of 32 feet per second per second.

以每秒32英尺的初速度做自由落体加速。

And since acceleration is measured as the change in meters per second, its units are meters per second per second -- otherwise known as meters per second, squared.

由于加速度是以米每秒的变化来衡量的，所以它的单位是米每秒——也就是米每秒的平方。

And there's no experiment that you could do that can tell the difference between an elevator in space moving upwards at 9.8 meters per second per second and an elevator sitting still on the surface of the earth.

没有任何实验可以告诉你在太空中以 9.8 m/s^2 的速度向上移动的电梯、和在地球表面静止不动的电梯之间的区别。