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 30 of 49.
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.
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.
Geeth said:
1 decade ago
Thank you all guys I got many ideas.
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.
Shikhar Singh said:
1 decade ago
Thanks for all related answer its easier for me too solve query like this.
Mayurkapse said:
1 decade ago
18/5 divided because the conversion of m/sec to km/hr.
Mandla npvks said:
1 decade ago
Solution: The train length is 125 m.
One man speed is 5 km/h. Time is 10 s.
The velocity of man with respect to train is v=distance/time.
125 m/10 s = 12.5 m/s.
We convert into km/h we multiplied with 18/5.
Then s = 12.5*18/5 = 45 km/h.
The train speed is 45+5 = 50 km/h.
One man speed is 5 km/h. Time is 10 s.
The velocity of man with respect to train is v=distance/time.
125 m/10 s = 12.5 m/s.
We convert into km/h we multiplied with 18/5.
Then s = 12.5*18/5 = 45 km/h.
The train speed is 45+5 = 50 km/h.
Dhamodharan.r said:
1 decade ago
What is the meaning of relative speed and also meaning of x-45=5?
Neeraja said:
1 decade ago
Why it is subtracted by 5?
Khushwanth said:
1 decade ago
HEY NEERAJA.
Distance = Time*Speed 125 = 10*Speed.
Distance/Time = Speed 125/10 = (25/2) m/s = Speed.
----------------------------------------------------------.
Answer should be in km/hr so convert m/s.
Km = 1000 m and hr = 3600 s.
M = km/1000 and s = hr/3600.
M/s = (3600/1000) km/hr.
M/s = (18/5) km/hr.
----------------------------------------------------------.
The condition was speed = (25/2) m/s.
= (25/2)(18/5) km/hr.
= 45 km/hr.
The speed was relative to man so we have taken time in consideration of man.
--------------------------------------------------------.
See further in in view answer.
Distance = Time*Speed 125 = 10*Speed.
Distance/Time = Speed 125/10 = (25/2) m/s = Speed.
----------------------------------------------------------.
Answer should be in km/hr so convert m/s.
Km = 1000 m and hr = 3600 s.
M = km/1000 and s = hr/3600.
M/s = (3600/1000) km/hr.
M/s = (18/5) km/hr.
----------------------------------------------------------.
The condition was speed = (25/2) m/s.
= (25/2)(18/5) km/hr.
= 45 km/hr.
The speed was relative to man so we have taken time in consideration of man.
--------------------------------------------------------.
See further in in view answer.
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