PHY 問題 速度deceleration 既問題
2008-05-28 3:42 am
A driver driving at 100 km h-1 on a straight highway sees a road-block 100m in front of him. If he wants to stop in front of it, what is the minimum deceleration of the car? Assume the reaction time of the drover is 0.5s .
回答 (1)
2008-05-28 3:52 am
✔ 最佳答案
Initial speed, u = 100kmh-1 = 100 X 1000 / 3600 = 27.78 ms-1Distance travelled during reaction time, s1
= ut1
= 27.78 (0.5)
= 13.89 m
Distance travelled during deceleration, s2 = 100 – s1 = 100 – 13.89 = 86.11 m
Final speed, v = 0
By equation of motion,
v2 = u2 + 2as2
0 = (27.78)2 + 2a(86.11)
Acceleration, a =-4.48 ms-2
So, the minimum deceleration of the car is 4.48 ms-2.
參考: Myself~~~
收錄日期: 2021-04-13 15:37:34
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080527000051KK02331