Problems on Trains
- 1. A train 800 metres long is running at a speed of 78 km/hr. If it crosses a tunnel in 1 minute, then the length of the tunnel (in meters) is:
Options- A. 130
- B. 360
- C. 500
- D. 540 Discuss
Correct Answer: 500
Explanation:
| Speed = | ❨ | 78 x | 5 | ❩ | m/sec | = | ❨ | 65 | ❩ | m/sec. |
| 18 | 3 |
Time = 1 minute = 60 seconds.
Let the length of the tunnel be x metres.
| Then, | ❨ | 800 + x | ❩ | = | 65 |
| 60 | 3 |
⟹ 3(800 + x) = 3900
⟹ x = 500.
- 2. A train 125 m long passes a man, running at 5 km/hr in the same direction in which the train is going, in 10 seconds. The speed of the train is:
Options- A. 45 km/hr
- B. 50 km/hr
- C. 54 km/hr
- D. 55 km/hr Discuss
Correct Answer: 50 km/hr
Explanation:
| Speed of the train relative to man = | ❨ | 125 | ❩m/sec |
| 10 |
| = | ❨ | 25 | ❩m/sec. |
| 2 |
| = | ❨ | 25 | x | 18 | ❩km/hr |
| 2 | 5 |
= 45 km/hr.
Let the speed of the train be x km/hr. Then, relative speed = (x - 5) km/hr.
∴ x - 5 = 45 ⟹ x = 50 km/hr.
- 3. Two goods train each 500 m long, are running in opposite directions on parallel tracks. Their speeds are 45 km/hr and 30 km/hr respectively. Find the time taken by the slower train to pass the driver of the faster one.
Options- A. 12 sec
- B. 24 sec
- C. 48 sec
- D. 60 sec Discuss
Correct Answer: 24 sec
Explanation:
| Relative speed = | = (45 + 30) km/hr | |||||||
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We have to find the time taken by the slower train to pass the DRIVER of the faster train and not the complete train.
So, distance covered = Length of the slower train.
Therefore, Distance covered = 500 m.
| ∴ Required time = | ❨ | 500 x | 6 | ❩ | = 24 sec. |
| 125 |
- 4. A jogger running at 9 kmph alongside a railway track in 240 metres ahead of the engine of a 120 metres long train running at 45 kmph in the same direction. In how much time will the train pass the jogger?
Options- A. 3.6 sec
- B. 18 sec
- C. 36 sec
- D. 72 sec Discuss
Correct Answer: 36 sec
Explanation:
Speed of train relative to jogger = (45 - 9) km/hr = 36 km/hr.
| = | ❨ | 36 x | 5 | ❩m/sec |
| 18 |
= 10 m/sec.
Distance to be covered = (240 + 120) m = 360 m.
- 5. Two trains are running in opposite directions with the same speed. If the length of each train is 120 metres and they cross each other in 12 seconds, then the speed of each train (in km/hr) is:
Options- A. 10
- B. 18
- C. 36
- D. 72 Discuss
Correct Answer: 36
Explanation:
Let the speed of each train be x m/sec.
Then, relative speed of the two trains = 2x m/sec.
| So, 2x = | (120 + 120) |
| 12 |
⟹ 2x = 20
⟹ x = 10.
| ∴ Speed of each train = 10 m/sec = | ❨ | 10 x | 18 | ❩ | km/hr = 36 km/hr. |
| 5 |
- 6. Two trains of equal lengths take 10 seconds and 15 seconds respectively to cross a telegraph post. If the length of each train be 120 metres, in what time (in seconds) will they cross each other travelling in opposite direction?
Options- A. 10
- B. 12
- C. 15
- D. 20 Discuss
Correct Answer: 12
Explanation:
| Speed of the first train = | ❨ | 120 | ❩ | m/sec = 12 m/sec. |
| 10 |
| Speed of the second train = | ❨ | 120 | ❩ | m/sec = 8 m/sec. |
| 15 |
Relative speed = (12 + 8) = 20 m/sec.
| ∴ Required time = | [ | (120 + 120) | ] | sec = 12 sec. |
| 20 |
- 7. 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:
Options- A. 9
- B. 9.6
- C. 10
- D. 10.8 Discuss
Correct Answer: 10.8
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 |
- 8. A train 110 metres long is running with a speed of 60 kmph. In what time will it pass a man who is running at 6 kmph in the direction opposite to that in which the train is going?
Options- A. 5 sec
- B. 6 sec
- C. 7 sec
- D. 10 sec Discuss
Correct Answer: 6 sec
Explanation:
Speed of train relative to man = (60 + 6) km/hr = 66 km/hr.
| = | ❨ | 66 x | 5 | ❩m/sec |
| 18 |
| = | ❨ | 55 | ❩m/sec. |
| 3 |
| ∴ Time taken to pass the man = | ❨ | 110 x | 3 | ❩sec = 6 sec. |
| 55 |
- 9. A train running at the speed of 60 km/hr crosses a pole in 9 seconds. What is the length of the train?
Options- A. 120 metres
- B. 180 metres
- C. 324 metres
- D. 150 metres Discuss
Correct Answer: 150 metres
Explanation:
| Speed = | ❨ | 60 x | 5 | ❩m/sec | = | ❨ | 50 | ❩m/sec. |
| 18 | 3 |
Length of the train = (Speed x Time).
| ∴ Length of the train = | ❨ | 50 | x 9 | ❩m = 150 m. |
| 3 |
- 10. A train travelling at a speed of 75 mph enters a tunnel 3½ miles long. The train is ¼ mile long. How long does it take for the train to pass through the tunnel from the moment the front enters to the moment the rear emerges?
Options- A. 2.5 min
- B. 3 min
- C. 3.2 min
- D. 3.5 min Discuss
Correct Answer: 3 min
Explanation:
| Total distance covered |
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| ∴ Time taken |
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| = 3 min. |
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