Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 26)
26.
Two trains are running at 40 km/hr and 20 km/hr respectively in the same direction. Fast train completely passes a man sitting in the slower train in 5 seconds. What is the length of the fast train?
Answer: Option
Explanation:
| Relative speed = (40 - 20) km/hr = |  |
20 x | 5 |  |
m/sec = | |
50 | |
m/sec. |
| 18 | 9 |
 Length of faster train = |
|
50 | x 5 | |
m = | 250 | m = 27 | 7 | m. |
| 9 | 9 | 9 |
Discussion:
72 comments Page 3 of 8.
J_k said:
1 decade ago
@Shweta.
If the train is travelling in same direction then we have to add both the speeds, if the train is travelling in opp. direction then we have to subtract them.
If the train is travelling in same direction then we have to add both the speeds, if the train is travelling in opp. direction then we have to subtract them.
Nidhi said:
1 decade ago
Can anybody tell me that, then how can we calculate the length of the slower train?
Shwetha said:
1 decade ago
Hey can anyone tell me why we have to take relative speed. When question is regarding fast train length?
Mancy said:
1 decade ago
Hi @Shweta.
We are taking relative speed because in the question direction of moving trains are mentioned so for calculating the length firstly we've to take relative speed.
We are taking relative speed because in the question direction of moving trains are mentioned so for calculating the length firstly we've to take relative speed.
Bhavya said:
1 decade ago
Relative speed =40-20= 20 is okay after why we multiplied with 5/18, and wt is that 5/18?
Sunny said:
1 decade ago
Please can anyone tell me the length of the slower train?
Sunny said:
1 decade ago
Here also the faster train crossing the slower train hence we get the length of 2 trains, not the faster train.
Alu said:
1 decade ago
What is that 18 denoting to in 5/18?
Ratnesh said:
1 decade ago
Hey to convert km/hr to m/s we have to use this conversion unit,
i.e 1000/(60*60)= 1000/3600.
Here 1 km = 1000 m and 1 hr = 60*60 =3600 seconds.
And when simplified it will give 5/18.
Hope your doubt about 18 would be clear now?
i.e 1000/(60*60)= 1000/3600.
Here 1 km = 1000 m and 1 hr = 60*60 =3600 seconds.
And when simplified it will give 5/18.
Hope your doubt about 18 would be clear now?
Divyansh said:
1 decade ago
When the question says this type that man is sitting but not tells the exact position the apply simple formula speed(Relative) = Distance/Time.
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