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:
475 comments Page 37 of 48.
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?
Bhavesh sharma/ gadgad786 said:
1 decade ago
Why we are multiplying the 18/5 ?
or we can ask that why we are divide ?
The answer is simple. We are converting the 'kilo-meters/hour' value into 'meters/second'.
Let me explain about converting km/hr into m/s in detail.
1 km = 1000 meters.
1 hr = 3600 seconds.
1 km/hr = 1000/3600 m/s
= 10/36 m/s
= 5/18 m/s.
Therefore 1 km/hr = 5/18 m/sec.
Similarly 60 km/hr = 60 x 5/18 m/sec.
You may ask me, why should I convert it from km/hr to m/sec?
or we can ask that why we are divide ?
The answer is simple. We are converting the 'kilo-meters/hour' value into 'meters/second'.
Let me explain about converting km/hr into m/s in detail.
1 km = 1000 meters.
1 hr = 3600 seconds.
1 km/hr = 1000/3600 m/s
= 10/36 m/s
= 5/18 m/s.
Therefore 1 km/hr = 5/18 m/sec.
Similarly 60 km/hr = 60 x 5/18 m/sec.
You may ask me, why should I convert it from km/hr to m/sec?
Sada said:
1 decade ago
Any basic formula is there for this problem kindly explain.
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?
Greeshma reddy said:
1 decade ago
How did this equation x-5=45 form?
Sanghaniakshay said:
1 decade ago
Thanks abhishek.
Ambikun said:
1 decade ago
There is no need of calculating relative speed. It can be solved easily by calculating the distance traveled by the man in 10 sec and the total distance covered by the train in the same time. This is very simple.
Parvez khan said:
1 decade ago
How was the relative speed calculated ?
Anish said:
1 decade ago
Hi Manishkumar,Vijaykumarkuppani,Umesh
U hav cleard the points exactly how itz done.
Thanks a lot...
U hav cleard the points exactly how itz done.
Thanks a lot...
Ranjit R Pawar said:
1 decade ago
Thanks rahul.
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