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:
487 comments Page 27 of 49.
Geeth said:
1 decade ago
Thank you all guys I got many ideas.
Swamy chukkala said:
1 decade ago
Well,
10 sec ----125 mt.
36 sec----- = (36/10)*125 = 450 mt = 450/10 = 45 + 5 = 50 km/hr.
10 sec ----125 mt.
36 sec----- = (36/10)*125 = 450 mt = 450/10 = 45 + 5 = 50 km/hr.
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.
Stark said:
1 decade ago
Correct your equation to 125/v1-(10*5)/(5*18) = 10 you will get.
v1 = 13.88 m/s.
==> v1 = 50 kmph.
v1 = 13.88 m/s.
==> v1 = 50 kmph.
Sai said:
1 decade ago
This concept is relative to distance not to time so you cannot take a relation like you have mentioned.
Samcena said:
1 decade ago
I made a relation like this (125m/v1-5*5/18) =10 sec. But the answer is not coming ? I converted 5 km/hr to m/s. Then I put it in above equation.
I put all the terms in m and sec (not in km and hour). My answer is coming to be 30. How is it? Help me out
I put all the terms in m and sec (not in km and hour). My answer is coming to be 30. How is it? Help me out
Deepak said:
1 decade ago
Nice trick.
Aayushi said:
1 decade ago
In 10 sec man will cover 125/9 m. In the relative motion distance should be added in either cases (opposite direction or same direction). So relative speed should be (125+(125/9))/10. Please explain.
Plabon said:
1 decade ago
Let the speed of train= x km/hr.
So relativee speed = distance/time.
Relative speed of train = (x- 5) km/hr.
x-5 = 0.125/10/3600.
So x- 5 = 0.125x3600/10 = 45.
x = 45+5 = 50 km/hr answer.
So relativee speed = distance/time.
Relative speed of train = (x- 5) km/hr.
x-5 = 0.125/10/3600.
So x- 5 = 0.125x3600/10 = 45.
x = 45+5 = 50 km/hr answer.
Rohit said:
1 decade ago
Why is the distance covered by man in 10 sec not considered? I believe the total distance would be the length of train + distance covered by man in 10 sec. Considering this the relative speed of train comes out to 55 km/hr. Please suggest.
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