✔ 最佳答案
設S為第1段的位移,
v=u+gt
3s/5=s/5+10*10
s=250m
v^2-u^2=2gh
(3s/5)^2-(s/5)^2=2*10*h
代入s=250m,
h=1000m
v^2-u^2=2gh
v^2-0^2=2*10*1000
v=141.4ms^-1
2008-11-27 23:07:47 補充:
以上做錯左= =,E到先岩
設S為第1段的位移,N為初速
V^2 - U^2 = 2G (3S)
U^2 - N^2 = 2G S
V^2-N^2 = 80S
呢度無問題啦
S=NT+( G ) ( T)^2 /2
= 5N + 125
V=N+GT=N+100
PUT S = 5N + 125
V=N+GT=N+100
INTO V^2-N^2 = 80S
N^2 +200N +10000 -N^2 = 80(5N+125)
200N+10000=400N+10000
N=0
2008-11-27 23:07:52 補充:
H= NT + (GT^2)1/2
= 0 + (10)(100) / 2
= 500
V^2 - N^2 = 2GS
V^2 - 0 = 2(10)(500)
V=100