Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 10)
10.
A jogger running at 9 kmph alongside a railway track in 240 metres ahead of the engine of a 120 metres long train running at 45 kmph in the same direction. In how much time will the train pass the jogger?
Answer: Option
Explanation:
Speed of train relative to jogger = (45 - 9) km/hr = 36 km/hr.
| = |  |
36 x | 5 |  m/sec |
| 18 |
= 10 m/sec.
Distance to be covered = (240 + 120) m = 360 m.
 Time taken = |
|
360 | sec |
= 36 sec. |
| 10 |
Discussion:
106 comments Page 2 of 11.
Pratik said:
7 years ago
@All.
I have a doubt. The jogger was not static. This means he/she must have covered some distance before the train crosses, all the solutions have not included this issue. Should I neglect that distance or is there anything I am missing.
To me, total distance = train length+ 240 metre+ the joggers covered path.
Is that correct or not. If not please help.
I have a doubt. The jogger was not static. This means he/she must have covered some distance before the train crosses, all the solutions have not included this issue. Should I neglect that distance or is there anything I am missing.
To me, total distance = train length+ 240 metre+ the joggers covered path.
Is that correct or not. If not please help.
Neerja said:
8 years ago
@Raj Vora.
The distance between the jogger and train is 240m so to first catch up to the jogger the train has to travel 240m. The length of the train is 120m so to completely pass the man and overtake him the train has to travel the length of the train, i.e. 120m.
Therefore total distance to be travelled by the train is 120m+240m=360m.
Hope this helped.
The distance between the jogger and train is 240m so to first catch up to the jogger the train has to travel 240m. The length of the train is 120m so to completely pass the man and overtake him the train has to travel the length of the train, i.e. 120m.
Therefore total distance to be travelled by the train is 120m+240m=360m.
Hope this helped.
Suriya said:
10 years ago
In any problem we will need to keep all the values in an uniform form, i.e. either all must be in m/sec or KM\hr.
In this problem they have converted from Km\Hr to m/sec. Therefore we multiply it my 1000/3600 (1 km = 1000 meters and 1 hour = 3600 seconds). When we cancel numerator and denominator we get, 5/18. This is how we get 5/18. Hope it helps.
In this problem they have converted from Km\Hr to m/sec. Therefore we multiply it my 1000/3600 (1 km = 1000 meters and 1 hour = 3600 seconds). When we cancel numerator and denominator we get, 5/18. This is how we get 5/18. Hope it helps.
Arpan Manchanda said:
6 years ago
@All.
Please let me know why we have considered the complete length of the track, may be jogger is in half of the way or but the question here is train is crossing jogger, they are running in the same direction hence we have considered relative velocity but when the train is passing a jogger, jogger don't have any length. Please elaborate.
Please let me know why we have considered the complete length of the track, may be jogger is in half of the way or but the question here is train is crossing jogger, they are running in the same direction hence we have considered relative velocity but when the train is passing a jogger, jogger don't have any length. Please elaborate.
Dheeraj Shenoy said:
4 years ago
The jogger is running at 9kmph.
240m ahead from 120m long train.
When the train covers 240m at speed of 45kmph in t = 96/5 sec in the same time the jogger covers 48m.
Since he is jogging at a particular speed so the total distance covered by the train to pass the jogger would be 120+240+48.
Then, how it could be 240 +120?
240m ahead from 120m long train.
When the train covers 240m at speed of 45kmph in t = 96/5 sec in the same time the jogger covers 48m.
Since he is jogging at a particular speed so the total distance covered by the train to pass the jogger would be 120+240+48.
Then, how it could be 240 +120?
(1)
Dheeraj Shenoy said:
4 years ago
The jogger is running at 9kmph.
240m ahead from 120m long train.
When the train covers 240m at speed of 45kmph in t = 96/5 sec in the same time the jogger covers 48m.
Since he is jogging at a particular speed so the total distance covered by the train to pass the jogger would be 120+240+48.
Then, how it could be 240 +120?
240m ahead from 120m long train.
When the train covers 240m at speed of 45kmph in t = 96/5 sec in the same time the jogger covers 48m.
Since he is jogging at a particular speed so the total distance covered by the train to pass the jogger would be 120+240+48.
Then, how it could be 240 +120?
Adarsh said:
8 years ago
Relative speed can be used only when the jogger covers 240 m in the said time. But he already is 240 m ahead of the train. Jogger is also moving, so he might also cover some distance, we have to calculate his distance. And we have to add that distance x +240 m + 120 meter. We have no idea about this distance x right?
Partha said:
1 decade ago
@Viji.T
i agree with u .. by the time the train approaches the jogger he/she would have covered some additional distance...how is that even possible to take the sum (240+120) as the total distance travelled ignoring the the distance covered by the jogger in that time interval...
i agree with u .. by the time the train approaches the jogger he/she would have covered some additional distance...how is that even possible to take the sum (240+120) as the total distance travelled ignoring the the distance covered by the jogger in that time interval...
Madhav Kulkarni said:
6 years ago
Speed of jogger=9km/h=9*(5/18)=2.5m/s.
Length=240.
Length of train = 120m.
Speed of train = 45km/h=45(5/18)=12.15m/s.
Relative Length=240+120=360m.
Relative speed=12.15-2.5=9.65m/s.
Speed = Distance/Time.
9.65 = 360/Time.
Time = 360/9.65.
= 36.
Length=240.
Length of train = 120m.
Speed of train = 45km/h=45(5/18)=12.15m/s.
Relative Length=240+120=360m.
Relative speed=12.15-2.5=9.65m/s.
Speed = Distance/Time.
9.65 = 360/Time.
Time = 360/9.65.
= 36.
Vedant said:
1 decade ago
@People considering distance traveled by jogger.
240 + 120 + 9*A (5/18) / (45*5/18) = A.
This will give A=36 so given solution is correct do no take relative speed concept just simply add distance to be covered and divide by train speed.
240 + 120 + 9*A (5/18) / (45*5/18) = A.
This will give A=36 so given solution is correct do no take relative speed concept just simply add distance to be covered and divide by train speed.
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