Problema Solution
A passenger train travels 55 miles per hour , and a freight train travels 31 miles per hour. When they run on parallel tracks in the same direction, they clear each other in 70 seconds. When they are traveling in the same direction on the same parallel tracks and the engines are exactly oppisite each other, they clear each other in 25 seconds. If the freight train is the longer, find the length of each train.
Answer provided by our tutors
Let Lf and Lp the length of the trains in miles and Vf and Vp their speeds in miles per hour.
Then in the first situation we have Lf=t1*(Vp-Vf) = 70*(55-31)/3600=0.466 miles
While in the second situation we have Lp+Lf=t2*(Vp+Vf) = 25*(55+31)/3600=0.597 miles
So Lf=0.466 miles and Lp=0.597-0.466 = 0.131 miles long.