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 1 of 48.
Swati said:
2 decades ago
Why is it divided by 18/5?
(1)
Jothi said:
2 decades ago
Please explain to sutract -5 but ans is 50.
(3)
M.saravanan said:
2 decades ago
Please explain 18/5.
(1)
Shwetha A V said:
2 decades ago
60*60/1000=18/5
(1)
Saji said:
2 decades ago
18/5 is to convert m/s to km/hr
(1)
Ankita said:
2 decades ago
Why its substracted?
(1)
Gowtham said:
2 decades ago
Hey why we findind relative speed??? They asking only speed na????
(1)
Vijayagopal said:
2 decades ago
Why 125/10 the 10 is divided 125 please explain it.
(2)
Rahul said:
2 decades ago
@gowtham
It would be only speed if the man(REFERENCE POINT) was stationary and only the train was moving. Here as both trian and REFERENCE POINT(man) are moving relative motion comes into picture.
It would be only speed if the man(REFERENCE POINT) was stationary and only the train was moving. Here as both trian and REFERENCE POINT(man) are moving relative motion comes into picture.
Rahul said:
2 decades ago
@ankita
when a man moves in the direction of train, the train speed is decreased by his own speed. If he moves in the opposite directon he finds the train speed to be much greater. So when is moving in the same direction his speed must be subtracted from that of train speed. If he moves in the opposite direction to that of train, then his speed must be added to the train speed.
moving in same directon: SUBTRACT
moving in opposite directon: ADD
when a man moves in the direction of train, the train speed is decreased by his own speed. If he moves in the opposite directon he finds the train speed to be much greater. So when is moving in the same direction his speed must be subtracted from that of train speed. If he moves in the opposite direction to that of train, then his speed must be added to the train speed.
moving in same directon: SUBTRACT
moving in opposite directon: ADD
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