Aptitude - Problems on Trains - Discussion
Discussion Forum : Problems on Trains - General Questions (Q.No. 14)
14.
Two trains 140 m and 160 m long run at the speed of 60 km/hr and 40 km/hr respectively in opposite directions on parallel tracks. The time (in seconds) which they take to cross each other, is:
Answer: Option
Explanation:
| Relative speed = (60 + 40) km/hr = |  |
100 x | 5 |  m/sec |
= | |
250 | m/sec. |
| 18 | 9 |
Distance covered in crossing each other = (140 + 160) m = 300 m.
| Required time = | |
300 x | 9 | sec |
= | 54 | sec = 10.8 sec. |
| 250 | 5 |
Discussion:
43 comments Page 5 of 5.
Indraneel Mal said:
3 years ago
72kmph = 20m/sec.
In 26 seconds, the distance covered = 20 * 26 = 520m.
As the length of the platform is 250m.
Therefore the length of the train = 520 - 250 = 270m.
In 26 seconds, the distance covered = 20 * 26 = 520m.
As the length of the platform is 250m.
Therefore the length of the train = 520 - 250 = 270m.
(5)
Akhil v said:
1 year ago
Thanks all for explaining the answer.
Akhil R said:
2 months ago
Formula:
Time = (L₁ + L₂) / (S₁ + S₂)
Given:
L₁ = 140 m.
L₂ = 160 m.
S₁ = 60 × 5/18 = 50/3 m/s.
S₂ = 40 × 5/18 = 100/9 m/s.
Substitute:
Time = (140 + 160)/(50/3 + 100/9).
Time = 300/(250/9).
Time = 300 × 9/250.
Time = 10.8 seconds.
Time = (L₁ + L₂) / (S₁ + S₂)
Given:
L₁ = 140 m.
L₂ = 160 m.
S₁ = 60 × 5/18 = 50/3 m/s.
S₂ = 40 × 5/18 = 100/9 m/s.
Substitute:
Time = (140 + 160)/(50/3 + 100/9).
Time = 300/(250/9).
Time = 300 × 9/250.
Time = 10.8 seconds.
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