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.
Lavanya said:
6 years ago
How to calculate 2x/36 = 25/9.
Pabitra said:
6 years ago
Hello, how do you take 5/18? please explain.
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.
RADHESHYAM KAMDE said:
6 years ago
Let the length of first train = L.
As we know that trains has equal length;
Therefore L+L = 2L.
And relative speed = 46-36 km/hr (because of the train are going the same direction, so we substrated it).
= 25/9 m/sec.
Time given in question = 36 sec.
We know;
Speed = distance/time.
25/9 = 2L/36,
L = 50 metre.
As we know that trains has equal length;
Therefore L+L = 2L.
And relative speed = 46-36 km/hr (because of the train are going the same direction, so we substrated it).
= 25/9 m/sec.
Time given in question = 36 sec.
We know;
Speed = distance/time.
25/9 = 2L/36,
L = 50 metre.
Ruchi chaubey said:
6 years ago
How did you take 2x?
Please explain.
Please explain.
Rutvik said:
6 years ago
Please explain 25/9=2.7m/s.
If we use the formula a+b/u-v and if the length is equal then 2a/2.7 = 36.
Which comes to 2a = 36 * 2.7.
i.e.a=36*2.7/2 which comes to 48.6.
Then how it will be 50?
If we use the formula a+b/u-v and if the length is equal then 2a/2.7 = 36.
Which comes to 2a = 36 * 2.7.
i.e.a=36*2.7/2 which comes to 48.6.
Then how it will be 50?
PAVAN said:
6 years ago
How do we get 2x/36 = 25/9?
Subba said:
6 years ago
@Sunny.
We know that speed = distance /time, here apply the same, but here since two trains are moving in the same direction relative speed comes and it is 10km/hr.
Then distance = 10 * 5/18 * 36 = 100metres.
Therefore, 2x = 100 and hence x = 50m each.
We know that speed = distance /time, here apply the same, but here since two trains are moving in the same direction relative speed comes and it is 10km/hr.
Then distance = 10 * 5/18 * 36 = 100metres.
Therefore, 2x = 100 and hence x = 50m each.
Sunny said:
6 years ago
How, 2x=100 comes?
Siree said:
6 years ago
s1-s2=(L1+L2)/time.
46-36=2(L1+L2)/36,
10 * 5/18=2(L1+L2)/36,
50=2(L1+L2)/2,
50*2=2(L+1L2).
L1+L2=100/2 = 50.
46-36=2(L1+L2)/36,
10 * 5/18=2(L1+L2)/36,
50=2(L1+L2)/2,
50*2=2(L+1L2).
L1+L2=100/2 = 50.
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