Find the length of a train, if ii completely crosses two bridges of lengths 600 m and 300 min 80 seconds and 60 seconds, respectively.

600 m

Let the length of train = D meter

Speed = \(\frac{DIstance}{Time}\)

Distance covered by train in 120 sec = (600 + D)

Speed = \(\frac{( 600 + D )}{120}\)     -------(1)

Distance covered by train in 80 sec = (300 + D)

Speed = \(\frac{( 600 + D )}{80}\)     --------(2)

Equating equation (1) and (2)

\(\frac{( 600 + D )}{120}\)  = \(\frac{( 600 + D )}{80}\)   

1200 + 2D = 900 + 3D

D = 300 m

So , Length of train is 300 m