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 11 of 11.
Chetan said:
2 decades ago
Relative speed means speed of an object w.r.t to another object.
Tips:
1.)Two objects moving in same direction-->stop object 2 and subtract object 2' s speed from object 1.
Ex: Suppose two cars moving in same direction with 60 kmph(both cars same speed)..it is obvious that relative speed is 0 kmph....how did it come??? by subtracting..ok.
2.) Two objects moving in oppsite direction--->stop obj 2 and add its speed to obj1.
Ex:
Car1 speed=40 kmph in east direction.
Car2 speed=50 kmph in west direction.
Relative speed of car1 w.r.t car2 is
stop car2, add its speed to car1, i.e 40+50 = 90.
Tips:
1.)Two objects moving in same direction-->stop object 2 and subtract object 2' s speed from object 1.
Ex: Suppose two cars moving in same direction with 60 kmph(both cars same speed)..it is obvious that relative speed is 0 kmph....how did it come??? by subtracting..ok.
2.) Two objects moving in oppsite direction--->stop obj 2 and add its speed to obj1.
Ex:
Car1 speed=40 kmph in east direction.
Car2 speed=50 kmph in west direction.
Relative speed of car1 w.r.t car2 is
stop car2, add its speed to car1, i.e 40+50 = 90.
Sarika said:
2 decades ago
Yes, karthik is right.
Karthik said:
2 decades ago
Relative speed= hidh speed + low speed when the objects are moving in the oppsite direction
Relative speed= hidh speed - low speed when the objects are moving in the same direction
Relative speed= hidh speed - low speed when the objects are moving in the same direction
Ramesh karthick said:
2 decades ago
Jogger is not idle. He also running. So we done this step 45-9km/hr.
9km/hr is jogger speed.
9km/hr is jogger speed.
RPrabha said:
2 decades ago
If in both the objects move in the same direction, the relative speed would be the sum of both the speeds. How is calculation is done. Even if tried with the mentioned procedure, the options don't have the derived answer
Karthik said:
2 decades ago
Y DID U substract 45-9? i didn't understand
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