Question

1．一列长360米的火车,匀速穿过一个长1800米的山洞.测得火车完全通过整个山洞的时间需3分45秒,求（1）该火车的速

Answer 1

1.(1)v=s/t=1800m+360m/225s=9.6m/s

(2)t=s/v=1800m-360m/9.6m/s=150s

2.(1)v=45*(1-1/3)/1.5h=20km/h

(2)t1=45km*1/3/30km/h=0.5h

t=0.5h+1.5h=2h

v=45km/2h=22.5km/h