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 5 of 24.
Appu said:
1 decade ago
Hello Friends,
If 2 trains of length a and b moving in same direction at u,v.Then the time taken by the faster train to cross the slower train is =(a+b)/(u-v)sec.
So here,Time=36sec and u+v=25/9m/sec
Then the formula is,36=(a+b)/(925/9)
a+b=100
Now we get a=50 and b=50
I think ur doubt is clear now
If 2 trains of length a and b moving in same direction at u,v.Then the time taken by the faster train to cross the slower train is =(a+b)/(u-v)sec.
So here,Time=36sec and u+v=25/9m/sec
Then the formula is,36=(a+b)/(925/9)
a+b=100
Now we get a=50 and b=50
I think ur doubt is clear now
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.
Arvind Kumar Sharma said:
1 decade ago
Lets take it as train t1 speed=46*(5/18)=115/9 m/sec.
and similarly train t2's speed= 36*(5/18)=10m/sec.
Now after 36 sec t1 will cover=36*(115/9)=460m
and t2 will cover=36*10=360m
So the difference between their head engine will be=460-360=100m
So the length of trains will 100/2=50 each
and similarly train t2's speed= 36*(5/18)=10m/sec.
Now after 36 sec t1 will cover=36*(115/9)=460m
and t2 will cover=36*10=360m
So the difference between their head engine will be=460-360=100m
So the length of trains will 100/2=50 each
Ali said:
1 decade ago
I think we can do it in a different way.
Distance = Speed*Time.
= (46-36) *5/18*36.
= 100.
This is the length of two trains.
And it is given that length of both the trains are equal.
Therefore length of one train is equal to 50.
Please some one suggest that it is correct or not.
Distance = Speed*Time.
= (46-36) *5/18*36.
= 100.
This is the length of two trains.
And it is given that length of both the trains are equal.
Therefore length of one train is equal to 50.
Please some one suggest that it is correct or not.
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.
Sahitya said:
2 years ago
speed of the train 1 = 46km/hr,
speed of the train 2 = 36km/hr,
Relative speed = 46 - 36 = 10km/hr.
t = 36sec.
10 * 5/18 = 50/18 m/sec.
S = d/t.
S = L1 + L2.
Here two trains have equal lengths.
So, its 2L1.
S = 2L1/t.
50/18 = 2L1/36.
L1 = 50m.
So, the length of each train is 50 m.
speed of the train 2 = 36km/hr,
Relative speed = 46 - 36 = 10km/hr.
t = 36sec.
10 * 5/18 = 50/18 m/sec.
S = d/t.
S = L1 + L2.
Here two trains have equal lengths.
So, its 2L1.
S = 2L1/t.
50/18 = 2L1/36.
L1 = 50m.
So, the length of each train is 50 m.
(15)
Ponjit said:
10 years ago
Since we are taking relative speed that means the slower train is stationary. And thus the faster train needs to travel only the distance of the slower train. Since both the trains start (assuming) at the same time and with the engines at the same line. The answer comes to be 100 m.
Saran kamaraj said:
9 years ago
As per the given condition, the faster train crosses the slower train. So it means that.
First,
The fast train crosses the slow train of distance x metre.
Second,
Note (the fast train is not a point,). So it has a length of x meter to cross.
Finally x + x = 2X.
Hope you get it.
First,
The fast train crosses the slow train of distance x metre.
Second,
Note (the fast train is not a point,). So it has a length of x meter to cross.
Finally x + x = 2X.
Hope you get it.
Pavani said:
4 weeks ago
The Length of L1 = length of L2.
L1 = L2.
So, length=2L.
Speed of the train t1 = 46km/hr.
Speed of the train t2 = 36km/hr.
The relative speed = t1 - t2 = 46 - 36 = 10km/hr.
convert to meters a = 10x5/18.
Then time = 36sec.
Now using formula:
2L = 10x5/18 x36.
2L = 100,
L = 50m.
L1 = L2.
So, length=2L.
Speed of the train t1 = 46km/hr.
Speed of the train t2 = 36km/hr.
The relative speed = t1 - t2 = 46 - 36 = 10km/hr.
convert to meters a = 10x5/18.
Then time = 36sec.
Now using formula:
2L = 10x5/18 x36.
2L = 100,
L = 50m.
(9)
Prity Manna said:
1 year ago
Length of two train = (x + x) = 2x m.
time 36 sec.
Speed = (46-36) = 10 * (5/18) = 25/9 m.
We know that if the train parallel lines in the same direction,
So, t = (L1+L2)/(S1-S2) sec,
so,36 = 2x/(25/9),
2x/36 = 25/9,
18x = 900,
x = 50.
Length of the train is 50 m.
time 36 sec.
Speed = (46-36) = 10 * (5/18) = 25/9 m.
We know that if the train parallel lines in the same direction,
So, t = (L1+L2)/(S1-S2) sec,
so,36 = 2x/(25/9),
2x/36 = 25/9,
18x = 900,
x = 50.
Length of the train is 50 m.
(39)
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