It's very interesting because velocity seems to require two different times to define it -- the initial time and the final time.

这非常有趣,因为速度似乎需要两个时间才能算出来,初时刻和末时刻

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So, the average is found by taking two instants in time, say t1 and later t2, and you find out where it was at t2 minus where it was at t1 and divide by the time.

平均速度就是取两个时刻,比如t1和之后的t2,用t2时刻的位移,减去t1时刻的位移,再除以这段时间

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