Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 22)
22.
Two goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.
Answer: Option
Explanation:
| Relative speed = | = (45 + 30) km/hr | |||||||
|
||||||||
|
We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.
So, distance covered = Length of the slower train.
Therefore, Distance covered = 500 m.
 Required time = |
 |
500 x | 6 |  |
= 24 sec. |
| 125 |
Discussion:
81 comments Page 2 of 9.
Dhiru said:
1 decade ago
Both trains driver meet first then time started not before meeting
E.g
Train 1.----------> Fastest train
Train 2. <------------ Slowest train.
If they go in the way adityabala said they will never meet. So both trains driver meet when time is ZERO or they never meet.
E.g
Train 1.----------> Fastest train
Train 2. <------------ Slowest train.
If they go in the way adityabala said they will never meet. So both trains driver meet when time is ZERO or they never meet.
Ramakhanna said:
1 decade ago
For the complete train to cross each other, it takes 48 sec.
To cross only the initial phase i.e. engine of first train facing the end of the second train. and engine of second train facing the end of the first train,it takes the half of the time to cross the complete train i.e. 48sec/2=24 sec.
To cross only the initial phase i.e. engine of first train facing the end of the second train. and engine of second train facing the end of the first train,it takes the half of the time to cross the complete train i.e. 48sec/2=24 sec.
Pallavi said:
8 years ago
The answer is simple. We are converting the 'kilo-meters/hour' value into 'meters/second'.
Let me explain about converting km/hr into m/s in detail.
1 km = 1000 meters.
1 hr = 3600 seconds.
1 km/hr = 1000/3600 m/s
= 10/36 m/s
= 5/18 m/s.
Therefore 1 km/hr = 5/18 m/sec.
Let me explain about converting km/hr into m/s in detail.
1 km = 1000 meters.
1 hr = 3600 seconds.
1 km/hr = 1000/3600 m/s
= 10/36 m/s
= 5/18 m/s.
Therefore 1 km/hr = 5/18 m/sec.
Sumit said:
1 decade ago
Nothing tricky. We have to understand the concept of relative speed.
Keeping the faster train static we can consider the speed of slower train as (30+45) km/hr and as train has to pass the driver. Distance taken is 500m.
Speed=75km/hr=75*5/18m/sec.
Time taken=24sec.
Keeping the faster train static we can consider the speed of slower train as (30+45) km/hr and as train has to pass the driver. Distance taken is 500m.
Speed=75km/hr=75*5/18m/sec.
Time taken=24sec.
Anoo said:
1 decade ago
If the question is given with specific term as driver, man in the train. We must neglect the train and only consider the driver or a man! hence you should take only train length (specified train neglecting the length of train in which man or driver is present).
Dineshgct said:
1 decade ago
Here they have asked only the time taken by the slower train to pass the driver of the faster train and not the length of the entire faster train.
So here we need to consider only the length of the slower train ie.500.
So,
Time=500\(75*5/18)
Which is 24sec.
So here we need to consider only the length of the slower train ie.500.
So,
Time=500\(75*5/18)
Which is 24sec.
Shro said:
1 decade ago
I agree with Pinku. If this is the way to find for slower train then what if the question is asked for faster train.
Even that will come as 24sec.
Then whats the use of asking slower and faster train in question?
OR is there any other method for it?
Even that will come as 24sec.
Then whats the use of asking slower and faster train in question?
OR is there any other method for it?
Ganda said:
8 years ago
Here answer should be 48 explain it with given example let the speed of the first train be 4m/s and second be 1m/s and length of trains be 5/5 m then you should make number line and get two seconds so we must add 5+5 10m and divides by 5m/ (1+4).
Jimmy said:
5 years ago
No @Vaidya,
24 is the right answer. Try to understand the question and then emulate the trains with two pens or pencils. You will realise that the question is asking about time taken to cover the length of only one train, not both.
24 is the right answer. Try to understand the question and then emulate the trains with two pens or pencils. You will realise that the question is asking about time taken to cover the length of only one train, not both.
Sandeep said:
1 decade ago
Its tricky one. I made mistake in first attempt. Because I didn't read the Question well and assumed that it is asking 4 the time taken to cross each other.
Good one.
We should understand the Question well before attempting it.
Good one.
We should understand the Question well before attempting it.
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