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:
478 comments Page 26 of 48.
MANAV said:
1 decade ago
Everything is ok and easy explanation.
But one thing is questionable.
If the train is crossing a man who is running in the same direction with a speed of 5km/hr, than than how the distance travelled in 10 secs is equal to the length of the train. Don't you think dear friends the distance travelled by the man should also be added to the length of the train.
But one thing is questionable.
If the train is crossing a man who is running in the same direction with a speed of 5km/hr, than than how the distance travelled in 10 secs is equal to the length of the train. Don't you think dear friends the distance travelled by the man should also be added to the length of the train.
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.
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