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 4 of 24.
Abdul said:
5 years ago
You can easily understand by assuming that one train is a brigde and its length is same as the train, let it be x and the speed of train is 10km/h (46-36).
Now, the time taken to cross the bridge is 36sec.
Dis = speed * time.
= (10*5/18) * 36.
= 100. Is that clear?
We know that 100 is the length of train+length of bridge.
We know both are same so 100÷2 = 50.
Train length is 50 and bridge(another train) length is 50.
Now, the time taken to cross the bridge is 36sec.
Dis = speed * time.
= (10*5/18) * 36.
= 100. Is that clear?
We know that 100 is the length of train+length of bridge.
We know both are same so 100÷2 = 50.
Train length is 50 and bridge(another train) length is 50.
(3)
Md. Habibur Rahman said:
5 years ago
When we calculated relative speed, Why we calculate 2x?
Relative speed means a train will be static. Then we can calculate x only. Am ai right? Please tell me.
Relative speed means a train will be static. Then we can calculate x only. Am ai right? Please tell me.
(1)
Vikrant said:
5 years ago
We have formula:
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 is taken by the faster train to cross the slower train = (a + b)/(u - v) Sec.
- Since two trains are of same length, so distance or(a+b) = 2x
- Time taken to cross slower train = 36 sec
- Speed of first train(u) = 46 kmph
- Speed of second train(v) = 36 kmph
- By applying formula ::
36 = 2x/((46-36)*(5/18)).
x = 50m.
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 is taken by the faster train to cross the slower train = (a + b)/(u - v) Sec.
- Since two trains are of same length, so distance or(a+b) = 2x
- Time taken to cross slower train = 36 sec
- Speed of first train(u) = 46 kmph
- Speed of second train(v) = 36 kmph
- By applying formula ::
36 = 2x/((46-36)*(5/18)).
x = 50m.
FERDAOUS HOSSAIN said:
5 years ago
Let, the length of each train is X m.
Both train length is (X+X) =2X m.
Relative speed (46-36) = 10 km/hr=25/9 m/sec.
As per the question,
2X/36 =25/9.
X=50.
Both train length is (X+X) =2X m.
Relative speed (46-36) = 10 km/hr=25/9 m/sec.
As per the question,
2X/36 =25/9.
X=50.
Mahesh Kariya said:
5 years ago
((46-36)X(5/18)) = (50/18) = (100/36).
2X = 100.
X = 50.
2X = 100.
X = 50.
(1)
Madhav said:
6 years ago
Since they are moving in same direction relative speed is;
46-36=10Km/h= 10*(5/18)= 2.77m/s.
Relative Speed is =2.77m/s.
Speed=Distance/Time.
Distance=Speed*time=2.77*36=99.9==100.
Here 2 train having equal length = D=L=l+l=2l.
2l=100
so l=50.
46-36=10Km/h= 10*(5/18)= 2.77m/s.
Relative Speed is =2.77m/s.
Speed=Distance/Time.
Distance=Speed*time=2.77*36=99.9==100.
Here 2 train having equal length = D=L=l+l=2l.
2l=100
so l=50.
(1)
Bushra Ahmed said:
6 years ago
From where did 100 come?
Bushra Ahmed said:
6 years ago
From where did 100 come?
Mahesh ojha said:
6 years ago
I think it the faster train has started from behind then only the answer is 50 meter. But if they started from the same point then the total distance covered be the only x.
Prashant Gupta said:
6 years ago
Relative length L.R = L1 + L2 = 2L.
Rel. SPEED ... (46- 36)5/18= 10m/s.
Relative Time... T.R =36.
Therefore,
L.R= R.S * R.T.
2L = 10 *36.
L = 50m.
Rel. SPEED ... (46- 36)5/18= 10m/s.
Relative Time... T.R =36.
Therefore,
L.R= R.S * R.T.
2L = 10 *36.
L = 50m.
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