1 54km/h=15m/s
300m/15s=20m/s
20m/s-15m/s=5m/s
2 (18-1)*50m=850m
850m/50s=17m/s
3 100m/800m/s=1/8s
1/8s*20m/s=2.5m
4 1min=60s 10km=10000m
50*10000*60*1=30000000=N
5 1/3 * 3/4 =1/4
6 72km/h=20m/s 20min=1200s 27km=27000m
(20m/s*1200s+27000m)/1200s+27000m/15m/s=17m/s
7 1min=60s
40m+80m=120m
120m/60s=2m/s
8 这里有个公式:2*v1*v2/v1+v2
设船速为v:2*(v-5)(v+5)/(v-5)+(v+5)=v平方-25=v
你自己去算吧
9 扶梯的速度:1
要走 72 级
兄弟,我已经尽力了,只能帮到这儿了,公式你就自己写吧,看我为你忙了这么长时间,拜托,给些分嘞.