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:
111 comments Page 5 of 12.
Himanshu said:
2 decades ago
Is there be any need to convert the speed and distance into mtrs? We could have been done it without converting to mtrs i.e. in kms only.
Nandhu said:
10 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.
Dipti said:
2 decades ago
Relative speed = (60+ 90) km/hr 150 is ok
= 150 x 5/18 m/sec
but how this 5/18 came
could you please discuss on this
= 150 x 5/18 m/sec
but how this 5/18 came
could you please discuss on this
Rajkumar said:
2 decades ago
You all use this formula and do the sum.
The sum which is in opposite direction.
So, formula for time=(L1+L2)/(S1+S2)sec
The sum which is in opposite direction.
So, formula for time=(L1+L2)/(S1+S2)sec
Vaideki said:
1 decade ago
HI Raj good job .its an easy way to find the answer.Same direction means (x+y)/(u-v) if it opposite means (x+Y)/(u+v)
B.K.S said:
1 decade ago
Length should always be added irrespective of direction and both trains are passing each other in same time interval.
Raghu said:
9 years ago
2km, when converted using formula, gives 5/9 m/s which is giving the wrong answer. Someone please explain this to me.
Ram said:
1 decade ago
They are starting at two different points and moving in opposite direction. They are not starting at the same point.
Kiran said:
2 decades ago
But can you tell me when we subtract (1.10km-0.9km)it becomes(0.2km)
then how can it becomes 2 km. Please explain.
then how can it becomes 2 km. Please explain.
God Here said:
2 years ago
@All.
Here's the solution:
Total distance = 2km;
total speed = 150;
time in seconds = (2/150)x3600 = 48 Answer.
Here's the solution:
Total distance = 2km;
total speed = 150;
time in seconds = (2/150)x3600 = 48 Answer.
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