We now know that light travels at precisely 299,792,458 metres per second.

我们现在已经精确地测出光速是每秒 299792458 米。

Time stops altogether on reaching the 299,792,458 metres per second at which light zaps through a vacuum.

当物体运动速度达到299792458米每秒时，即达到光在真空中的传播速度时，时间整体停止。

For the 100 metres, the human speed limit is 10.55 metres per second. This translates to 9.48 seconds.

就100米而言，人类的速度极限是每秒10.55米。这也就是说（最短时间是）9.48秒。

Ultrasonic waves travel at around 300 metres per second.

【second】超声波的传播速度约为每秒 300 米。

That's about 10 metres per second or 36.8 kilometres per hour.

这大约是每秒 10 米或每小时 36.8 公里。

In order to avoid erosion the very tips  of the blades cannot spin faster than 90 metres per second.

为了避免腐蚀，叶片尖端的旋转速度不能超过每秒 90 米。

In this top graph of the red wiggly line, we're looking at the ground velocity in essentially metres per second. So, that's the velocity that the ground is vibrating up and down.

在这张红色波浪线的顶部图中，我们看到的是地面速度，单位是米/秒。这就是地面上下振动的速度。