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 3 of 11.
Priyanka said:
1 decade ago
Can you explain me why in this question relative speed is subtaction of higher speed to lower while in same direction relative speed is addition of both object speed?
Jelli said:
1 decade ago
Hi
i think you can use the formula
u=(a+b)/(u-v) (both in a same dir)
=(120+240)/(45-9)*5/18
=36s
i think you can use the formula
u=(a+b)/(u-v) (both in a same dir)
=(120+240)/(45-9)*5/18
=36s
Sumi said:
1 decade ago
hi priyanka u understood wrongly relative speed for the objects in same direction is obtained by subtracting only
Dheeraj said:
1 decade ago
@rprabha... no when two things are going in same direction then realtive speed is not sum of that things..
Viji said:
1 decade ago
Any body please explain that the relative speed calculation for both speed and distance when opposite and same direction moving ?
Harika said:
1 decade ago
When we have to calculate relative speed?
Viji.T said:
1 decade ago
The distance taken here is not clear for me. They use the term ahead of the engine like that. What they mean there. To take a distance as (120+240) , what is the logic behind that. Please can anyone explain me?
Deepak agrawal said:
1 decade ago
@Harika
we calculate the ralative speed when two object are run simultenously in parallel .
we calculate the ralative speed when two object are run simultenously in parallel .
Aditya bala said:
1 decade ago
We calculate relative speed for opposite and same direction if they travel in opposite direction we add them, in same direction we substract them.
M.V.Rama Krishna Kumar Reddy said:
1 decade ago
For the same direction we get relative speed by subtracting speeds.
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