Question

If two track tunnel of length 430m. Two trains of length 270m and300m enters from opposite direction with the speed of 54km/hr and 36 km/hr respectively. Find the time gap the tunnel remains free from train when the trains crosses each other completely.

Answer 1

Sol : √8 + 4√32 - 6√2

     = √(2 x 2 x 2 ) + 4√( 2 x 2 x 2 x 2 x 2 ) - 6√2

    = √( 4 x 2 )  + 4√( 16 x 2 ) - 6√2

We have √4 = 2 and √16 = 4.

Now,
    = 2√2 + 4 x 4 √2 - 6√2

   = 2√2 + 16√2 - 6√2

   = √2 ( 2 + 16 - 6 )

  = √2 ( 18 - 6 )

  = √2 x 12

  = 12√2.Ans.