Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option
Explanation:
| Relative speed = (40 - 20) km/hr = |  |
20 x | 5 |  |
m/sec = | |
50 | |
m/sec. |
| 18 | 9 |
 Length of faster train = |
|
50 | x 5 | |
m = | 250 | m = 27 | 7 | m. |
| 9 | 9 | 9 |
Discussion:
72 comments Page 1 of 8.
Subha said:
1 decade ago
According to the formula given here we can find the SUM OF LENGTH OF THE 2 TRAINS and not the length of the faster train which is asked in the question.
Arun said:
1 decade ago
Hi subha... @ not like dat ma...dats in d case if d faster train crosses d slower train... But in dis case d train just crosses a man(which may be considered as a point)....
Haritha said:
1 decade ago
Hi guys but the train crosses a man who is sitting in the train but not the one who is standing simply. Also he might be sitting in middle or some where else we have to calculate the distance from which the man is sitting. Isn't it?
Haritha said:
1 decade ago
Could anyone please explain me clearly?
Gargi said:
1 decade ago
Hey guys Haritha was right! It's also not clear to me.
Manasa said:
1 decade ago
What arun said was correct. You consider that man as reference point. Then we can get length of the faster train.
Thank you ARUN.
Thank you ARUN.
Shanmu said:
1 decade ago
We are calculating only the fastest train length know. So where ever the man is sitting the trains length will not vary know guys.
Antrinitz singh said:
1 decade ago
I can't understand anything can anyone explain with formula.
Shareef said:
1 decade ago
1)First calculate the relative speed of two trains ( as they are moving in same direction it will be difference of two train speeds).
Relative speed = 40-20 = 20 km/hr = 20*5/18 =50/9 m/s
2)Now faster crosses the man sitting in the slower one (irrespective of the position of man it may be starting,middle or last) now use the formula
length of train (faster) = speed X time = 50/9*5 = 27 7/9 m
Relative speed = 40-20 = 20 km/hr = 20*5/18 =50/9 m/s
2)Now faster crosses the man sitting in the slower one (irrespective of the position of man it may be starting,middle or last) now use the formula
length of train (faster) = speed X time = 50/9*5 = 27 7/9 m
Ram said:
1 decade ago
Just ignore second train(ie., slow train) and assume man is running with 20km/hr speed. Both are in same direction.
Relative speed = 40-20 = 20 kmph.
Relative speed = 40-20 = 20 kmph.
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