Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 2)
2.
A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
Answer: Option
Explanation:
| Speed of the train relative to man = |  |
125 |  m/sec |
| 10 |
| = | |
25 | m/sec. |
| 2 |
| = | |
25 | x | 18 | km/hr |
| 2 | 5 |
= 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.
x - 5 = 45 
x = 50 km/hr.
Discussion:
493 comments Page 22 of 50.
Deepak said:
1 decade ago
In first problem you mentioned that meters per sec is equal to 5/18 but then you are taking like 18/5 why so please tell me.
Nishant said:
9 years ago
But it should have been given that we have to find the relative velocity of the man. So, 45km/hr should be the right answer.
Iliyas said:
4 years ago
m/sec = [1/1000 km] / [1/3600 sec]
= [1/1000] *[3600/1],
= [3600/1000].
= [18/5]km/hr.
= [1/1000] *[3600/1],
= [3600/1000].
= [18/5]km/hr.
(28)
Vishu said:
9 years ago
Hey guys for the same question. How to find the time taken by the train to overtake the man. Instead of finding the speed?
Angel said:
9 years ago
@Bala.
Speed=(Distance/Time).
Here distance is the length of the train which is 125 m and the time is 10 s
speed=125/10.
Speed=(Distance/Time).
Here distance is the length of the train which is 125 m and the time is 10 s
speed=125/10.
Revathi said:
1 decade ago
Nice explanations are there but still I have a doubt. Can anyone tell me which speed has to subtract in relative motion?
Shikha said:
1 decade ago
Why did we take relative speed twice ?
Once with the main i.e 125/10 * 18/5 then again, x- 5.
Please clarify my doubt.
Once with the main i.e 125/10 * 18/5 then again, x- 5.
Please clarify my doubt.
Nil said:
1 decade ago
If we convert km/hr into m/sec i.e. 1000/3600 it's come 5/18. So why it is calculation is 125/10*18/5 instead of 5/18?
Sonu said:
6 years ago
x-5 = 45.
x = 45+5(because when 5 goes from the left side to right then it will be added into 45).
So,
x = 50 Answer.
x = 45+5(because when 5 goes from the left side to right then it will be added into 45).
So,
x = 50 Answer.
PRADYUMNA KUMAR DAS said:
1 decade ago
If the man and train in opposite direction then it relative speed is x+5. And speed is x+5=45. =>x=40. Am I right?
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