a.b兩列火車,a車長1000米,b車長2000米,a車以80km/小時的速度從c點往東勻速行駛,半小時后b車以81km/小時的速度從c點沿著a車行駛的軌道同向勻速而行,問,以b車出發開始計時,多長時間后b車行程和a車行程相等?
An electric train is traveling northwest at 95 miles per hour, and the wind is blowing southwest at 95 miles per hour. In which direction does the smoke blow?
一輛電動火車每小時95英里的速度往西北開,大風以95英里的速度往東北吹,請問火車的煙往哪個方向飛?