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.
Vinayak said:
1 decade ago
Can we calculate this example by (a+b) / (u-v)?
Hasi said:
1 decade ago
Distance traveled by train =x
2 trains have same length
there are two trains traveled at the same time
means total distance traveled by the train =2x
Relative distance of the train is =(46-36)=10km/hr
but options are given in sec so,we have to convert into m/sec
10*(5/18)=25/9
total distance=speed*time
2x=(25/9)*36
2x=100
x=50
2 trains have same length
there are two trains traveled at the same time
means total distance traveled by the train =2x
Relative distance of the train is =(46-36)=10km/hr
but options are given in sec so,we have to convert into m/sec
10*(5/18)=25/9
total distance=speed*time
2x=(25/9)*36
2x=100
x=50
Arup said:
1 decade ago
Why we have to subtract (46-36)kmph?
though it is relative speed and both of them are coming to each other it should get added i.e (46+36)
though it is relative speed and both of them are coming to each other it should get added i.e (46+36)
Rajkumar said:
1 decade ago
Equal length, L1=L2
speed s1,s2
in same direction formula, time=(L1+L2)/(s1-s2) m/sec.
s1=46 km/hr
s2=36 km/hr
time=36 sec
time=(L1+L2)/(46-36)*5/18
36=(L1+L1)/(10)*5/18 [:.Equal length, L1=L2]
36=2L/(50/18)
36=(2L*18)/50
2L=(36*50)/18
2L=100
L=50 m
Using this formula.
speed s1,s2
in same direction formula, time=(L1+L2)/(s1-s2) m/sec.
s1=46 km/hr
s2=36 km/hr
time=36 sec
time=(L1+L2)/(46-36)*5/18
36=(L1+L1)/(10)*5/18 [:.Equal length, L1=L2]
36=2L/(50/18)
36=(2L*18)/50
2L=(36*50)/18
2L=100
L=50 m
Using this formula.
Ram Chaudhary said:
1 decade ago
Here the length of first train is x meters
and the distance covered by the two train is 2x meters
{Here we have to convert km/hr into m/sec because the answer is in the meter}
Relative speed between them is ((46-36)*))5/18 then we get
25/9 m/sec
after that we must equating the two equations then we get the length of the first train
we are using the formula distance=time*speed
distance=2x
time=36 sec
speed=25/9
2x=25/9*36
we get x=50 m
and the distance covered by the two train is 2x meters
{Here we have to convert km/hr into m/sec because the answer is in the meter}
Relative speed between them is ((46-36)*))5/18 then we get
25/9 m/sec
after that we must equating the two equations then we get the length of the first train
we are using the formula distance=time*speed
distance=2x
time=36 sec
speed=25/9
2x=25/9*36
we get x=50 m
Krupa said:
1 decade ago
The 2x is bcoz
Let the length of the train a =x
Length of the train b =y since both the trains are equal in length uwe can take
Length of train b as also "x"
So, Distance=x+x=2x
simple :-)
Let the length of the train a =x
Length of the train b =y since both the trains are equal in length uwe can take
Length of train b as also "x"
So, Distance=x+x=2x
simple :-)
Kuddush alam said:
1 decade ago
How can we take 2X there?
Swaroop said:
1 decade ago
"The faster train passes the slower train in 36 seconds" as mentioned in Question i.e First Train is behind the second Train and it crosses second train in 36 sec.
Therefore distance travelled in 36 sec is, length of second train and also length of first train. Hence the distance is 2x.
Therefore distance travelled in 36 sec is, length of second train and also length of first train. Hence the distance is 2x.
Suntth said:
1 decade ago
How the relative velocity is V2-V1? Since tthe trains are in same direction, velocity shall be V1+V2
Balaji said:
1 decade ago
Here what is mentioning by 18/5 or 5/18... have some confusion
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