文理..velocity

2008-05-31 6:43 pm
A police patrol car is travelling at a constant speed when it is passed by a speeding car. The police accerlerate at 3m/s2 for 5 seconds until it catches up with the speeding car which is travelling at 30m/s . What was the initial speed of the police car??

緊急架...!thx

回答 (2)

2008-05-31 7:55 pm
✔ 最佳答案
If I does not interpret the question wrongly, applying
s = ut + 1/2 a t^2
30(5) = 5u+ 0.5(3)(5^2)
u = 22.5m/s


If velocity of police car is 30m/s finally then applying
v= u + at
30= u + 5(3)
u= 15m/s
2008-06-01 1:29 am
有加速度(accerleration),有最後的速度(velocity),有時間(time),想找初速?
用公式v=u+at,代入a等如3,v第如30,t等如5
得出,30=u+3x5。最後,u等如15m/s。
仲有,你看完之後自己算一次,公式考試是會提供但不代表可以不認識。自己溫一溫speed同velocity的關係,我保証你本身分得不太清楚。

2008-05-31 17:45:43 補充:
上面果個你好搞笑,二條式算出兩個答案你不會奇怪嗎?
你第一條式個s一定不是30乘5,都話一路加速,個s又點止30乘5?
參考: me


收錄日期: 2021-04-13 15:38:18
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20080531000051KK00704

檢視 Wayback Machine 備份