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:
234 comments Page 7 of 24.
UMAR farooq said:
8 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.
Swadhin said:
8 years ago
Thanks everyone.
Kiran H said:
8 years ago
(Length of a train+Length of the train)/(time is taken by the train to cover the length) = Relative speed of two trains.
Let X be the length of the train.
(X+X)/36 = (46-36) {in km/hr convert it into m/s),
2X/36 = 10*(5/18),
X/18 = 50/18.
Therefore X= 50.
Let X be the length of the train.
(X+X)/36 = (46-36) {in km/hr convert it into m/s),
2X/36 = 10*(5/18),
X/18 = 50/18.
Therefore X= 50.
Ritika said:
8 years ago
Thanks, @Prati.
You explained it in the very simple way.
You explained it in the very simple way.
Rgvkalp said:
8 years ago
We should consider also the length of the two trains as the faster train can overcome by its length and the slower train.
Therefore, the distance travelled by fa aster train is 2x.
Therefore, the distance travelled by fa aster train is 2x.
Durgesh Kumar Gupta said:
8 years ago
Why not consider the length of the faster train? Please explain me.
Ritik said:
8 years ago
We should consider the extreme case, where starting point of faster train coincides with the finishing point of slower train.
Aminul Islam said:
8 years ago
Let, the length of each train be x metres.
In 36 seconds The faster train passes the slower one. so total distance covered by two train is 2x metres sharp 36 seconds.
According to formula 9 given above,
t = (a+b)/(u-v).
or, 36 = (x+x)/(46-36),
or, 36 = 2x/(46-36)*5/18 (to change km/hr to m/s,multiflied by 5/18).
x = (36/2)*(25/9),
= 50.
In 36 seconds The faster train passes the slower one. so total distance covered by two train is 2x metres sharp 36 seconds.
According to formula 9 given above,
t = (a+b)/(u-v).
or, 36 = (x+x)/(46-36),
or, 36 = 2x/(46-36)*5/18 (to change km/hr to m/s,multiflied by 5/18).
x = (36/2)*(25/9),
= 50.
Sarang said:
8 years ago
Distance = speed * time,
D = 46-36= 10* time,
D = 10 5/18* 36,
D= 10 * 5 * 2 = 100,
The length both train is 100/2 = 50.
D = 46-36= 10* time,
D = 10 5/18* 36,
D= 10 * 5 * 2 = 100,
The length both train is 100/2 = 50.
Shashi said:
8 years ago
Why the distance covered is taken as 2x?
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