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

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?

Found 2 solutions by khwang, ohthatstheanswer:
Answer by khwang(438) (Show Source): You can put this solution on YOUR website!

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.
Answer by ohthatstheanswer(1) (Show Source): 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
RELATED QUESTIONS
Thanks for your help. Shouldn't the 500 meters be converted to .5km and the 1000... (answered by Alan3354)
Two trains T1 & T2 travelling in opposite directions,on parallel tracks,are just... (answered by mananth)
Two trains are on the same track going in opposite directions. One is traveling at 55 mph (answered by tommyt3rd)
Two trains leave Dallas traveling the same direction on parallel tracks. One train is... (answered by mananth)
Two trains, one 350 feet long, the other 450 feet long, on parallel tracks, can pass each (answered by ankor@dixie-net.com)
Question: A freight train that is 1 mile long is traveling at 60 mph. A second train... (answered by solver91311)
Two trains, each of length 125 metre, are running in parallel tracks in opposite... (answered by mananth)
An eastbound train and a westbound train meet each other on parallel tracks heading in... (answered by mananth)
It takes 12 seconds for the two trains to pass one another when moving in opposite... (answered by ankor@dixie-net.com)