SOLUTION: Two trains, one 500 meters long and the other 1000 meters long, are traveling in opposite directions on parallel tracks. The first train is traveling at 100km/h and the other at 8
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Question 1157: Two trains, one 500 meters long and the other 1000 meters long, are traveling in opposite directions on parallel tracks. The first train is traveling at 100km/h and the other at 80km/h. How long will it take for the trains to pass each other from the moment the locomotives are at the same point?
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The diagram as below.
500 m 100 km/h ->
A<------>B (1st train)
C<------------->D (2nd train)
<- 80 km/h 1000 m
When they pass each other after t hrs,diagram as
A B
<------>
<------------->
C D
After t hrs, B moves 100 t km and C moves 80 t km.
So we have 100 t + 80 t = BC = CD + AB = 1000+ 500
So, 180 t = 1500, t = 25/3 hrs
[Or get t by (1000+ 500)/(100+80) directly.
Answer: it takes 25/3 hrs for the trains to pass each other
from the moment the locomotives are at the same point.
Or get t by (1000 + 500)/ (1000+ 60) directly.
You can put this solution on YOUR website! ||||||||--}|||||
|||||||||||{---- are the trains at the moment they are at the same point.
|||||--}||||||||
{----||||||||||| are the trains after passing each other.
Thus, the distance for the two trains to pass each other completely is 500m + 1000m = 1.5km
(d)istance = (v)elocity x (t)ime
Thus, the time required for the trains to pass each other is t = d / v =
-> 1.5km/(100km/h + 80 km/h) = 1.5km/180km/hr
-> km cancels out -> convert to min
-> (1.5 x 60min/hr)/180/hr
-> hr cancels out
-> 90min/180
-> 1min/2 = 30s to completely pass each other
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