Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 9)
9.
Two trains are moving in opposite directions @ 60 km/hr and 90 km/hr. Their lengths are 1.10 km and 0.9 km respectively. The time taken by the slower train to cross the faster train in seconds is:
Answer: Option
Explanation:
Relative speed = (60+ 90) km/hr
| = |  |
150 x | 5 |  m/sec |
| 18 |
| = | |
125 | m/sec. |
| 3 |
Distance covered = (1.10 + 0.9) km = 2 km = 2000 m.
| Required time = | |
2000 x | 3 | sec = 48 sec. |
| 125 |
Discussion:
107 comments Page 10 of 11.
Suriya mohan said:
9 years ago
When two trains travel in parallel, then the time of train must be subtracted or added?
JITESH DABANGG said:
9 years ago
Now im telling how the answer came 48 sec and doubt about 125/3.
See, the relative speed of the train in the opposite direction will be always A + B.
THEN, 90 + 60 = 150 KM/HR.
Then convert into m/s 150 * 5/18 = 125/3 clear,
Now total distance = 2 km = 2000mtr,
Required time = (2000/125/3.
= 2000/1*3/125 = 48 answer in above question this step is by passed because this is common thing which is everyone knows.
See, the relative speed of the train in the opposite direction will be always A + B.
THEN, 90 + 60 = 150 KM/HR.
Then convert into m/s 150 * 5/18 = 125/3 clear,
Now total distance = 2 km = 2000mtr,
Required time = (2000/125/3.
= 2000/1*3/125 = 48 answer in above question this step is by passed because this is common thing which is everyone knows.
Nandhu said:
9 years ago
Speed = 60 + 90.
= 150km/hr.
Length = 1.1 + 0.9.
= 2km.
Time = length/speed.
= 2/150,
= 1/75 hr (1 hr=3600s),
= 3600/75 s,
= 48sec.
= 150km/hr.
Length = 1.1 + 0.9.
= 2km.
Time = length/speed.
= 2/150,
= 1/75 hr (1 hr=3600s),
= 3600/75 s,
= 48sec.
Surya said:
9 years ago
2km/150km/hr * 3600.
Answer 48sec.
Answer 48sec.
Vijju said:
8 years ago
Here we need to consider the only length of faster trains because the question asked for the time taken by slower to pass fast train. So that what I think we need to consider relative speed but faster train length.
Sriram said:
8 years ago
How you take covered distance as 2km?
Sainath said:
8 years ago
Then, What will be the time taken by faster train to cross slower train?
Raghu said:
8 years ago
2km, when converted using formula, gives 5/9 m/s which is giving the wrong answer. Someone please explain this to me.
Pankaj said:
7 years ago
Hi, the time taken by faster train to cross slower & time taken by slower train to cross faster will be same, right?
So why are we using relative speed formula for all the time. We can use a+b/u+v for calculating time.
So why are we using relative speed formula for all the time. We can use a+b/u+v for calculating time.
Ram said:
7 years ago
Guys, can anyone explain how 41.6666667 was turn into 125/3?
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