Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 7)
7.
Two trains of equal length are running on parallel lines in the same direction at 46 km/hr and 36 km/hr. The faster train passes the slower train in 36 seconds. The length of each train is:
Answer: Option
Explanation:
Let the length of each train be x metres.
Then, distance covered = 2x metres.
Relative speed = (46 - 36) km/hr
| = |  |
10 x | 5 |  m/sec |
| 18 |
| = | |
25 | m/sec |
| 9 |
 |
2x | = | 25 |
| 36 | 9 |
2x = 100
x = 50.
Discussion:
232 comments Page 8 of 24.
Sunil said:
7 years ago
Since they are in same speed u,v.
We take u-v=46-36=10km/hr,
10*5/18=25/9,
So now we know the speed and time,
25/9 * 36 = 100.
As we calculated for the 2 trains we require only the length of one train so we take 100/2=50.
We take u-v=46-36=10km/hr,
10*5/18=25/9,
So now we know the speed and time,
25/9 * 36 = 100.
As we calculated for the 2 trains we require only the length of one train so we take 100/2=50.
Shro said:
1 decade ago
For all those who got doubt why 46-36?
Its because both train are moving in same direction.
So as per the formula when moving in same direction.it should be subtracted.
When moving in opposite direction,it should be added.
Its because both train are moving in same direction.
So as per the formula when moving in same direction.it should be subtracted.
When moving in opposite direction,it should be added.
Aparna said:
1 decade ago
Let the train A started at the end of other train B. So, it has to first cover the whole length of the train B and to completely cross B it has to cover additional length of the train A. So, length=2*lenth of each train.
Ster said:
1 decade ago
2x as distance only makes sense if the faster train start behind the slower train. If they were right next to each other at the start, the distance traveled would only be x. Question does not clarify this. Please amend.
Zia said:
1 decade ago
The distance covered is (X+X) = 2X.
Let, the speed of 1st&2nd train as x & y.
So, Apply the formula,
5/18(x-y)*T (T as time) = 5/18(46-36)*36.
= 50*36/18.
= 100.
So, we have 2X = 100.
X = 100/2 = 50 m.
Let, the speed of 1st&2nd train as x & y.
So, Apply the formula,
5/18(x-y)*T (T as time) = 5/18(46-36)*36.
= 50*36/18.
= 100.
So, we have 2X = 100.
X = 100/2 = 50 m.
Ghanshyam said:
1 decade ago
There is some data is not given properly that the faster train start from ending point of slower train that's why the answer is 100 meters and if the trains start from same point at that time answer is 100 meters.
UMAR farooq said:
7 years ago
First, it has to pass its complete length then it crosses the slowest train means;
First it takes 18 sec to travel its own length then it takes another 18 sec to cross the slowest train that's why 2x it is taken.
First it takes 18 sec to travel its own length then it takes another 18 sec to cross the slowest train that's why 2x it is taken.
Shaik Chereesh said:
4 years ago
Relative displacement is x not 2x.
The relative speed is 10.
Time is independent of the frame of reference.
The above points are correct according to my basic knowledge of physics.
Please correct me if the wrong.
The relative speed is 10.
Time is independent of the frame of reference.
The above points are correct according to my basic knowledge of physics.
Please correct me if the wrong.
Aditya said:
5 months ago
@SRIRAM.
We have to add both train lengths assume with your hand both hands cross each other now slow the process when your left hand and right hand meet the length of your left-hand and right-hand not subtract.
We have to add both train lengths assume with your hand both hands cross each other now slow the process when your left hand and right hand meet the length of your left-hand and right-hand not subtract.
(2)
Vasanthvasu said:
2 decades ago
Length of the train =X m
by converting it into km...........
(X/36)*(18/5)=X/10 KM
X/10 = 46-36 = 10
X=100
both are same length
therefore
2X=100 ..... LENGTH OF BOTH TRAIN
X=50........ LENGTH OF EACH TRAIN
by converting it into km...........
(X/36)*(18/5)=X/10 KM
X/10 = 46-36 = 10
X=100
both are same length
therefore
2X=100 ..... LENGTH OF BOTH TRAIN
X=50........ LENGTH OF EACH TRAIN
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