✔ 最佳答案
1. Let u be the starting speed and v be the final speed
since average speed increases each hr by 5, in 5hours time, v = u+50
(v-u)/t=a(i) with constant acceleration
(u+50-u)/5=a
a=10km hr^-2
s=ut+1/2 at^2
300=5u+1/2*10*25
u=35km/hr
s=ut+1/2at^2
s=35*1.5+1/2*10*2.25
s=63.75km
(b)
10m/s=36km/hr (Nice, you are kidding me)
so in 5 hours time, v=u-360
(u-360+u)/5=a
a=-72km hr^-2
300=5u+1/2(-72)*25
u=240km/hr (What a speed)
s=240(.75)+1/2(-72)(.75)^2
=159.75km (Satisfy with it?)
2. 88
3. 2 (assume you are using 10進制 and this is a maths question)
2007-04-15 22:41:44 補充：
我好得閒回應d玩野o既題目架......
1+1+?=100
有冇人會寫88呀?
我想同你講byebye啫
