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 5 of 8.
Raja.k said:
1 decade ago
@Swetha.
According to this question two trains are in same starting points only but the speed of the two trains is varying. So, anyway we subtract this. Did you understand now.
According to this question two trains are in same starting points only but the speed of the two trains is varying. So, anyway we subtract this. Did you understand now.
Sindhu said:
1 decade ago
If the two trains are moving in the same direction their relative speeds are subtracted.
Shweta said:
1 decade ago
Can anyone tell me when we have to add relative speed and when we have to subtract?
Sadik ali said:
1 decade ago
How can we find speed of slower train?
Qasim said:
1 decade ago
Thanks ram. That one is really good example.
Gaurav said:
1 decade ago
As the man is sitting in the train, he has the same speed as of train, so it simply means that the faster train crosses the slower train in 5 seconds.
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
Antrinitz singh said:
1 decade ago
I can't understand anything can anyone explain with formula.
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.
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.
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