Question

a train 100m long is to cross a river bridge of length 800m. what time will it take to cross a bridge?given that the train moves with a constant velocity of 30 km/h

Answer 1

Total distance covered by the train = (100+800)m

                                                          = 900 m

The speed of the train in m/s = (30*5/18) m/s

                                                = (5*5/3) m/s

                                                = 25/3 m/s

25/3 m is covered in 1 second

1 m is covered in (3/25) second

900 m is covered in (3*900/25) second

                                 = (3*36) second

                                 = 108 second

                                 = (108/60) minute [ 1 minute = 60 seconds.]

                                 = 1 minute 48 seconds.

(Ans): 1 minute 48 seconds.

Answer 2

Answer:

108.04seconds

Step-by-step explanation:

To cross bridge completely engine of train has to travel 100m (ie it’s length) more in addition to bridge length of 800m.

So total distance to be travelled =900m

Speed=30km/h

          =30*5/18

         =8.33m/s

Therefore

Time taken = distance/speed

= 900/8.33

Time Taken=108.04seconds

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