Train into a Tunnel


An express train takes 3 seconds to enter the tunnel which is 1 km long.
If it is travelling at 120 km an hour, how long will it take to pass completely through the tunnel?

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    33 Seconds

    The train travels at 120 km/h = 120,000m/h

    i.e.,  120,000 / 3,600 m/s

    It ‘takes 3 seconds to enter the tunnel‘ means it takes 3 sec. for the entire length of the train to pass the entrance of the tunnel.

    Hence, the length of the train = distance covered kin 3 sec. = 120,000 / 3,600 * 3 = 100m

    To completely pass through the tunnel, the total distance to be covered = length of tunnel + length of train = 1100m (1km + 100m)

    Since the train takes 3 sec. to cover 100m, time taken to cover the 1,100m = 33 Sec.

    Viji_Pinarayi Expert Answered on 5th August 2022.
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