# Problems on Trains

Problems on Trains - Important Points

1. | A train 800 m long is running at a speed of 78 km/hr. If it crosses a bridge in 1 minute, then the length of the bridge is: |
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A. 540 m

B. 130 m

C. 500 m

D. 260 m

View Answer Discuss Work SpaceAnswer: option c

Explanation:

Given, Length of the train = 800 m,

Speed of the train = 78 km/hr (convert km/hr to m/sec) = 78 * (5/18) m /sec = 21.667 m /sec

=> Speed of the train = 21.667 m /sec.

Time taken by the train to cross the bridge = 1 min = 60 sec.

Time taken by train to cross bridge = (Length of bridge + Length of train) / speed of the train

=> 60 = (Length of bridge + 800) / 21.667

=> 60 * 21.667 = Length of bridge + 800

=> 1300 = Length of bridge + 800

=> 1300 – 800 = Length of bridge

=> **Length of bridge = 500 m**

2. | A train 360 m long is running at the speed of 45 km/hr. The time taken by it to pass a bridge 140 m long is: |
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A. 48 seconds

B. 42 seconds

C. 40 seconds

D. 45 seconds

View Answer Discuss Work SpaceAnswer: option c

Explanation:

Given, Length of train =360 m

Length of bridge =140 m

Speed of train = 45 km/hr

=> Converting into meter/ second

= 45 * (5/18) m / sec

= 12.5 m/sec

=> Speed of train = 12.5 m/sec

**Required Time = (Length of train +Length of bridge) / Speed of train**

= (360 + 140) / 12.5

= 500 / 12.5

= 40 sec

=> Required Time = 40 secs

3. | How much time does a train 110 metres long running at the speed of 72 km/hr take to cross a bridge 132 metres in length? |
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A. 14.3 seconds

B. 12.1 seconds

C. 9.8 seconds

D. 12.42 seconds

View Answer Discuss Work SpaceAnswer: option b

Explanation:

Given, Length of train = 110 metres

Speed of passenger train =72 km/hr

=> Converting Speed from km/hr into m/sec

=> Speed of passenger train = 72 * (5/18) m/sec

= 4 * 5

= 20 m/sec

Length of bridge =132 metres

**Time taken by the train to cross the bridge = (Length of the passenger train + Length of the bridge) / Speed of train**

= (110 + 132) / 20

= 242 / 20

= 12.1 secs

Time taken by the train to cross the bridge = 12.1 seconds

4. | A passenger train 280 m long, running with a speed of 63 km/hr will pass a pole in: |
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A. 15 seconds

B. 20 seconds

C. 18 seconds

D. 16 seconds

View Answer Discuss Work SpaceAnswer: option d

Explanation:

Given, Length of the passenger train = 280 m

Speed of the passenger train = 63 km / hr

=> To convert km/hr to m/sec multiply speed with (5 / 18)

= 63 x (5 / 18) m/sec

= 17.5 m/sec

**Time taken by the train to cross a pole = Length of the passenger train / Speed of the passenger train**

= 280/17.5

= 16 secs

5. | In what time will a train 100 metres long cross a pole, if its speed is 144 km/hr? |
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A. 25 seconds

B. 5 seconds

C. 12.5 seconds

D. 2.5 seconds

View Answer Discuss Work SpaceAnswer: option d

Explanation:

Given, Length of the passenger train = 100 m

Speed of the train = 144 km / hr

=> To convertkm/hr to m/sec multiply speed with (5 / 18)

= 144 x (5 / 18) m/sec

= 40 m/sec

Time taken by the train to cross pole = Length of the train / Speed of the train

T = 100 / 40

= 2.5 sec