甲乙两车在同一条平直公路上同向匀速前进,甲车在半小时内行驶9km,乙车在 5min内,

问题描述:

甲乙两车在同一条平直公路上同向匀速前进,甲车在半小时内行驶9km,乙车在 5min内,
甲乙两车在同一条平直公路上同向匀速前进,甲车在半小时内行驶9km,乙车在
5min内,行驶1200m,乙车上桥后1min,甲车才到桥上,甲车追及乙车时,两车恰好同时下桥,求桥长.

V甲=x甲/t甲=9000m/1800s=5m/s
V乙=x乙/t乙=1200m/(5x60s)=4m/s
L/V乙+L/V甲=to
L/4m/s+L/5m/s=60s L=1200m