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:
476 comments Page 22 of 48.
Vishu said:
8 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:
8 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:
9 years 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:
5 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?
Anbu said:
1 decade ago
Just try this 1 sec 5 km/hr means 10 sec is 50 km/hr thats it..
becoz the man running at same time train is moving ..
becoz the man running at same time train is moving ..
Anvesh said:
1 decade ago
l=125m;
s=5*5/18;
t=10s;
l=t*s;
s=t/l;
s=125/10;
s=12.5*18/5;
the man was also going same direction so,
s=45+5;
s=50;
s=5*5/18;
t=10s;
l=t*s;
s=t/l;
s=125/10;
s=12.5*18/5;
the man was also going same direction so,
s=45+5;
s=50;
Akansha said:
1 decade ago
18/5 is used to change meter per second to kilometer per hour.
And I have no idea why it says -5 as it should be +5.
And I have no idea why it says -5 as it should be +5.
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