Now, I would think that it is reasonable to ask the following question: What is the average velocity, for instance, between time zero and time four?

现在，我认为,提出如下问题,是十分合理的：,比如说，平均速度是多少，在0到4秒之间？

youdao

The average acceleration 2 between time t1 and time t2 2 would then be the velocity at time t2 minus the velocity at time t1, divided by t2 minus t1.

在t1和t2之间的，这段平均加速度2，等于t2时刻的速度2，减去t 1时速度，再除以。

youdao

And now you will understand how we define the instantaneous velocity at time t which is different from an average velocity between two time intervals.

现在明白了吗，t时刻，的瞬时速度是怎样定义的，与两时刻间的平均速度相比，瞬时速度并不一样。

youdao