A police car is patrolling on a straight highway at 108 km/h. When a speeding car travelling at 144 km/h passes the police car and is 10m in front of it, it starts to accelerate and chases the speeding car. If the police car accelerates uniformly at 5 ms^-2 and the speeding car moves with a constant speed, how long will it take for the police car to catch up with the speeding car?
Ans: 4.83 s
究竟點計出泥嫁>
(好似要用 s = ut + ½at² 呢條式)
Physics問題!!! (Motion) 10點~~
2012-04-01 1:10 am
回答 (1)
2012-04-01 1:21 am
✔ 最佳答案
Given v_p = 108km/h, for p = policev_c = 144km/h, for c = car
For police car,
s_p = 108(1000)/(3600)t + 5t^2 /2 = 30t + 2.5t^2-----------(1)
For the car,
s_c = 144(1000)/(3600)t = 40t ---------------(2)
s_p = s_c + 10
30t+2.5t^2 = 40t+10
t^2 - 4t = 4
t^2 - 4t - 4 = 0
t = 4.83s or -0.83s(rej,t>0)
參考: Hope the solution can help you%^^”
收錄日期: 2021-04-23 23:38:27
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20120331000051KK00539