SOLUTION: 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 sl

Question 346023: 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 ankor@dixie-net.com(22740) (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?
:
Let a = speed of the faster train
let b = speed of the slower
:
Trains meeting each other
The sum of the speed of the two trains (in meters/sec)
speed = dist/time
a + b =
a + b = 20.83 m/sec is the sum of their speeds
:
Trains going in the same direction (change 3 min to 180 sec
a - b =
a - b = 1.39 m/sec is the difference of their speed
:
Use elimination
a + b = 20.83
a - b = 1.39
----------------adding eliminates b, find a
2a = 22.22
a =
a = 11.11 m/sec is the speed of train a
In km/hr: ~ 40 km/hr
:
then using the sum equation find b
11.11 + b = 20.83
b = 20.83 - 11.11
b = 9.72 m/sec is the speed of train b
In km/hr ~ 35 km/hr

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