There is a racing car running on a straight road. The car starts from rest and ahs a constand acceleration of 4.0 ms^-2. At the moment shown in the figure, the reading on the speedometer of the car is 90km/h.
a). Find the time required
b), Fidnt he distance travelled for the car to attain the speed of 90km/h
physics (motion)
2008-12-27 8:58 pm
回答 (2)
2008-12-27 9:50 pm
✔ 最佳答案
a)90km/h
=90*1000/3600m/s
=25m/s
v=u+at
25=0+4(t)
t=6.25s
b)
s=ut+(1/2)at2
s=0(6.25)+(1/2)(4)(6.252)
s=78.1m
(在會考中,答案應取至3位有效數字!)
(在a part中,應先列明將90km/h轉為m/s的計算步驟!)
參考: myself
2008-12-27 9:14 pm
a: v=u+at
25=4t
t=6.25s
b:s=ut+1/2at^2
s=1/2(4)(6.25^2)
s=78.125m
25=4t
t=6.25s
b:s=ut+1/2at^2
s=1/2(4)(6.25^2)
s=78.125m
收錄日期: 2021-04-25 23:15:13
原文連結 [永久失效]:
https://hk.answers.yahoo.com/question/index?qid=20081227000051KK00694