標題:
A question
發問:
Explain it clearly. 1. A girl walks on a straight road from A to B with constant speed of 2m/s. Then she walks from B back to A with constant speed of 3m/s. If A and B are 10m apart, what is her average speed for the whole trip?
最佳解答:
Time spent from A to B = 10/2 s = 5 s Time spent from B to A = 10/3 s = 3.33 s total time of journey = (5 + 3.33) s = 8.33 s Total distance covered = (10+10) m = 20 m hence, average speed = distance/time = 20/8.33 m/s = 2.4 m/s
其他解答:
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