Question 775842: It takes 12 seconds for two trains to pass one another when moving in opposite directions. If they are in the same direction, it will take the faster train 3 minutes to pass the slower one. If the trains are 130 meters and 120 meters long, respectively, what are the rates of the two trains?
Answer by mananth(16946)   (Show Source):
You can put this solution on YOUR website! It takes 12 seconds for two trains to pass one another when moving in opposite directions. If they are in the same direction, it will take the faster train 3 minutes to pass the slower one. If the trains are 130 meters and 120 meters long, respectively, what are the rates of the two trains?
train I speed = x
train II speed =y
When they are in opposite direction the effective speed = x+y
Time taken = 12 seconds = 12/3600 hrs. = 1/300 hours
The total length of trains is the distance d=250 m = 0.25 km
Distance = speed * time
(x+y)*1/300 =0. 250
When in same direction
effective speed = x-y
time = 3 minutes = 3/60 = 1/20 hours
(x-y)*1/20 = 0.250
(x+y)*1/300 = 0.250
x+y = 75
x-y= 5
Add the two equations
2x=80
/2
x=40 => speed of Train I
x+y=75
so speed of Train II = 75-40=35 kph
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