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 3 of 24.
Joydeep mukherjee said:
1 decade ago
There are two train A and B:
Let, the length of train A = X meter.
And, the length of train B also = X meter.
Then, the total length = (A+B) = (X+X) = 2X meter.
Relative speed = (46-36) km/hr = 10km/hr.
[Because, one train is faster then other].
Then, convert into m/sec = 10*5/18 = 25/9 m/sec.
As we know, Speed = Length/Time.
25/9 = 2X/36.
X = 50 [ by solving].
Let, the length of train A = X meter.
And, the length of train B also = X meter.
Then, the total length = (A+B) = (X+X) = 2X meter.
Relative speed = (46-36) km/hr = 10km/hr.
[Because, one train is faster then other].
Then, convert into m/sec = 10*5/18 = 25/9 m/sec.
As we know, Speed = Length/Time.
25/9 = 2X/36.
X = 50 [ by solving].
Umair said:
1 decade ago
We use this formula in that question
If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s, then:
The time taken by the faster train to cross the slower train = (_a+b)_____ sec.
(u - v)
but there is some changes in this formula when distance is same we use 2x where we use a+b as the distance of a+b two different distance
If two trains of length a metres and b metres are moving in the same direction at u m/s and v m/s, then:
The time taken by the faster train to cross the slower train = (_a+b)_____ sec.
(u - v)
but there is some changes in this formula when distance is same we use 2x where we use a+b as the distance of a+b two different distance
Santosh said:
1 decade ago
When two bodies are moving in different speed may be opposite or same direction then the effective speed called relative speed..
assume one body moving x speed another y speed...then the relative speed like this,
relative speed = (x-y) when both body moving same direction
relative speed = (x+y) when both body moving opposite direction
...just like average buddy....
assume one body moving x speed another y speed...then the relative speed like this,
relative speed = (x-y) when both body moving same direction
relative speed = (x+y) when both body moving opposite direction
...just like average buddy....
Sridharsan said:
8 years ago
The first train covered a distance of 460m in 36s and the second one covered 360 m in 36s, at the moments of 36th second the distance between trains is 100 mtr, above said the answer is 50mtr, that is the fastest train is 50mtr away from the other one. That is, the train also passes before reaching 36s. If the question is true the answer would 100 mtr. Am I right?
Nishil Stephen said:
10 years ago
Train = ||.
Train 1 = |1| speed is 46 km.
Train 2 = [2] speed is 36 km.
*Diagram:
1. Imagine at (2:00 am) both are moving in parallel direction.
[2] (T1 haven't covered x distance).
|1| at (2:00:36 am).
|1| [2] (T1 covers first x distance).
# At (2:01:13 am).
|1| (T1 covers next x distance).
[2] ((Now t1 coverd 2x distance)).
That's how distance is 2x.
Train 1 = |1| speed is 46 km.
Train 2 = [2] speed is 36 km.
*Diagram:
1. Imagine at (2:00 am) both are moving in parallel direction.
[2] (T1 haven't covered x distance).
|1| at (2:00:36 am).
|1| [2] (T1 covers first x distance).
# At (2:01:13 am).
|1| (T1 covers next x distance).
[2] ((Now t1 coverd 2x distance)).
That's how distance is 2x.
Paddy said:
1 decade ago
If both are of same length but time taken by A to cross B is given i.e 36 minutes, it does not mean that the B train is at Rest.
B is also moving so total distance cover by A = length of A + length of B + some distance after starting.
Total dist travel by B = 360 m
Total dist travel by A = 460 m
Therefore diff is 100 m
i.e. Length of train A or B
B is also moving so total distance cover by A = length of A + length of B + some distance after starting.
Total dist travel by B = 360 m
Total dist travel by A = 460 m
Therefore diff is 100 m
i.e. Length of train A or B
Kiran said:
1 decade ago
Speed = distance/time.
Here they have given that two trains are running parallel i.e., S1 & S2.
Relative speed = S1-S2 => 46-36 = 10kmph.
Now we have to convert kmph into m/sec.
So 10x5/18 = 25/9.
Speed = 25/9.
Time = 36 secs.
=>distance = speed x time.
=>25/9x36.
=>100 (length of the two trains).
Length of the each train = 50.
Here they have given that two trains are running parallel i.e., S1 & S2.
Relative speed = S1-S2 => 46-36 = 10kmph.
Now we have to convert kmph into m/sec.
So 10x5/18 = 25/9.
Speed = 25/9.
Time = 36 secs.
=>distance = speed x time.
=>25/9x36.
=>100 (length of the two trains).
Length of the each train = 50.
Yash said:
6 years ago
What is happening here is that:
Train 1 is running at the speed of 36km/hr.
Now, train 2 which is running at 46km/hr crosses the train 1, means it comes from behind and the whole train goes ahead of train 1.
So, first it travels x distance i.e. length of train1&2 to reach side by side of train 1 and x distance to cross it.
Hence, distance 2x.
Train 1 is running at the speed of 36km/hr.
Now, train 2 which is running at 46km/hr crosses the train 1, means it comes from behind and the whole train goes ahead of train 1.
So, first it travels x distance i.e. length of train1&2 to reach side by side of train 1 and x distance to cross it.
Hence, distance 2x.
Shoeb said:
1 decade ago
In the question it's clearly mentioned two trains are of same length.
So we can use formula , two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u - v) m/s.
* So 46-36=10km/hr.
* 10 *5/18 : 25/9
* 25/9*36 :.100 ( both train )
* 100/2=50 each train.
Thanks.
So we can use formula , two trains or two objects bodies are moving in the same direction at u m/s and v m/s, where u > v, then their relative speed is = (u - v) m/s.
* So 46-36=10km/hr.
* 10 *5/18 : 25/9
* 25/9*36 :.100 ( both train )
* 100/2=50 each train.
Thanks.
Aminul Islam said:
7 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.
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