因此，边缘上的点每1.8秒必须比中心的点多转50英寸，使它不得不在同样的时间里覆盖不到五分之一的距离。

So the point on the edge must rotate much faster to cover that 50 in. in 1.8 seconds than the point near the center, which has to cover less than a fifth of the distance in the same time.

youdao

在电梯中按“关门”钮的时候(顺带说一句，这是世间80%电梯内的机械镇定剂)，或者是在微波炉转咖啡的30秒内再干一件别的什么任务。

Pressing the "close doors" button in a lift (incidentally, a mechanical placebo in 80% of lifts around the world), or using the 30 seconds while the microwave heats my coffee for another task.

youdao

5秒转一圈。

The thing goes around once in 2.5 seconds.

youdao

If it takes you 1 / 60 of a second to go around once, then you do it 60 times a second.

如果转一圈要 1 / 60 秒,那么一秒就转了60圈

耶鲁公开课 - 基础物理课程节选

Frequencies, how many times you go around, f is revolutions per second It's called the angle of velocity.

频率就是一秒转多少圈,因为 f 是每秒转过的圈数,这就是角速度

耶鲁公开课 - 基础物理课程节选