Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 7)
7.
Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is:
Answer: Option
Explanation:
Let the length of each train be x metres.
Then, distance covered = 2x metres.
Relative speed = (46 - 36) km/hr
| = |  |
10 x | 5 |  m/sec |
| 18 |
| = | |
25 | m/sec |
| 9 |
 |
2x | = | 25 |
| 36 | 9 |
2x = 100
x = 50.
Discussion:
235 comments Page 12 of 24.
Ankit said:
1 decade ago
I think the answer should be 100 meters, because in question it is not given the starting positions of trains. So we have to assume they started from same point.
Now let the slower train is at rest then the faster train's speed would be 10 km/hr, and it cross the slower train (length) in 36 sec. So the LENGTH = 10km/hr*30 sec = 100 meters.
Now let the slower train is at rest then the faster train's speed would be 10 km/hr, and it cross the slower train (length) in 36 sec. So the LENGTH = 10km/hr*30 sec = 100 meters.
Nishil Stephen said:
1 decade ago
Train = ||.
Train 1 = |1| speed is 46 km.
Train 2 = [2] speed is 36 km.
*Diagram:
1. Imagine at (2:00 am) both are moving in parallel direction.
[2] (T1 haven't covered x distance).
|1| at (2:00:36 am).
|1| [2] (T1 covers first x distance).
# At (2:01:13 am).
|1| (T1 covers next x distance).
[2] ((Now t1 coverd 2x distance)).
That's how distance is 2x.
Train 1 = |1| speed is 46 km.
Train 2 = [2] speed is 36 km.
*Diagram:
1. Imagine at (2:00 am) both are moving in parallel direction.
[2] (T1 haven't covered x distance).
|1| at (2:00:36 am).
|1| [2] (T1 covers first x distance).
# At (2:01:13 am).
|1| (T1 covers next x distance).
[2] ((Now t1 coverd 2x distance)).
That's how distance is 2x.
Mounika said:
1 decade ago
We are finding the relative speed.
Kousalya said:
1 decade ago
My question is why we are including ten in the calculation its not given in the data right?
Prasun jana said:
1 decade ago
Fast train 46*(5/18)*36 = 460.
2nd train 36*(5/18)*36 = 360.
Difference = 460-360 = 100.
2 train = 100/2 = 50 (ans).
2nd train 36*(5/18)*36 = 360.
Difference = 460-360 = 100.
2 train = 100/2 = 50 (ans).
Malli said:
1 decade ago
Friends he said it takes 36 sec to cross a train then it means the difference in distance b/n them is x (which is length of train).
So the answer is:
x/(Relative speed) = 36;
x = 100;
Not 50 its wrong.
So the answer is:
x/(Relative speed) = 36;
x = 100;
Not 50 its wrong.
Ponjit said:
1 decade ago
Since we are taking relative speed that means the slower train is stationary. And thus the faster train needs to travel only the distance of the slower train. Since both the trains start (assuming) at the same time and with the engines at the same line. The answer comes to be 100 m.
Viswanath said:
1 decade ago
As two trains are in parallel (same direction). So we can subtract the speeds of other trains. Relative speed is (25/9) m/sec.
NOTE: Time in contact of 2 trains at a time MEANS the time at which faster train engine meet the last part of slower train TO faster train last part meet the engine of slower train.
Both trains relative speed = Distance of 2 trains/(Time in contact of 2 trains at a time).
(25/9) m/sec = 2x/36.
NOTE: Time in contact of 2 trains at a time MEANS the time at which faster train engine meet the last part of slower train TO faster train last part meet the engine of slower train.
Both trains relative speed = Distance of 2 trains/(Time in contact of 2 trains at a time).
(25/9) m/sec = 2x/36.
Patani said:
1 decade ago
2x/36=25/9 why use 36?
SAM said:
1 decade ago
Why should we take relative speed is (46-36) in this case they are parallel?
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