In a 100m race, a runner accelerates from rest at 3.3ms^-2 and reaches a
maximum velocity of 10ms^-1. she then maintains this velocity for the rest of the race.
what is her finishing time?
f.4 physics
2009-09-24 5:17 am
回答 (1)
2009-09-24 5:25 am
✔ 最佳答案
Consider the journey when she is accelerating.By v = u + at1
10 = 0 + 3.3t1
Time, t1 = 3.03 s
By v2 = u2 + 2as1
(10)2 = 0 + 2(3.3)s1
Distance, s1 = 15.15 m
So, the remaining distance = 100 - 15.15 = 84.85 m
Therefore, the remaining time = s / v = 84.85 / 10 = 8.485 s
Therefore, the finishing time
= 8.485 + 3.03
= 11.5 s
Or you may use the v-t graph to solve the problem.
參考: Physics king
收錄日期: 2021-04-19 15:23:07
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https://hk.answers.yahoo.com/question/index?qid=20090923000051KK01652