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 15 of 48.
Pradeep said:
1 decade ago
Can you please explain me what is relative speed here and why it is used here ?
Nagaraj said:
1 decade ago
It should be taken as 1000/60*60 beacuse distance covered/ time taken.
M.kanna said:
1 decade ago
18/5 explanation is super k/m h/r put 1000/3600=5/18 answer is very nice apserve then nice.
Mahendra said:
1 decade ago
Nice explanation sheela thank you all who commented.
Pradeep said:
1 decade ago
From The Question 5Km/hr So please explain it 1000/3600. give me reason.
KIRUBHA said:
1 decade ago
FRNDS is it correct or not tell me plz....
MAN'S SPEED = 5 KM/HR
Train length =125 m.
let assume train speed=x.
then we get relative speed (rs) of train and man is become
rs=x-5.
To conver km/hr into m/s.
= (x-5) / (5/18)
= 5x-25 / 18
speed = distance/time
125/10 = 5x-25 / 18
2250 = 50x-250
x = 2000 / 50
x = 40
Is it correct?
MAN'S SPEED = 5 KM/HR
Train length =125 m.
let assume train speed=x.
then we get relative speed (rs) of train and man is become
rs=x-5.
To conver km/hr into m/s.
= (x-5) / (5/18)
= 5x-25 / 18
speed = distance/time
125/10 = 5x-25 / 18
2250 = 50x-250
x = 2000 / 50
x = 40
Is it correct?
Swapnil....... said:
1 decade ago
Why is it addition of 45km/hr & 5km/hr?
Because I thing train & man is going to same direction that time sutract but in this case addition of 45km/Hr & 5km/hr please explain it why is it addition.
Because I thing train & man is going to same direction that time sutract but in this case addition of 45km/Hr & 5km/hr please explain it why is it addition.
Challu said:
1 decade ago
Think you are in a train, another one moving side by you in parallel, what will you experience? the train is in less speed of actualone. To find original speed you have to add your train speed.
Preethi said:
1 decade ago
You are right kirubha. Nice explanation challu.
Preethi said:
1 decade ago
Thanks Abhishek now I clear about relative speed.
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