Question 52050
A passenger train travelled at a speed of 72 km/h. 

A man on the passenger train observed a goods train travelling at a speed of 54 km/h  in the opposite direction.
RELATIVE SPEED OF 2 TRAINS TRAVELLING OPPOSITE TO EACH OTHER = 72+54
=126 KMPH..=126000/3600 M/SEC=1260/36=210/6=35 M/SEC
IF YOU DO NOT UNDERSTAND THIS CONCEPT REFER MY EARLIER SOLUTIONS ON THIS TOPIC OR PLEASE COME BACK.
 If the goods train passed him in 8 seconds, find the length of the good train. 
GOODS TRAIN PASSES MEANS FROM THE TIME PASSENGER SEES ITS FIRST BOGIE (SAY ENGINE) TO THE TIME HE SEES ITS LAST BOGIE..THAT IS A DISTANCE TRAVELLED EQUAL TO LENGTH OF GOODS TRAIN = L SAY
TIME = 6SEC.
L=35 *6 = 210 M.

(Hint : Model the problem and draw a diagram). NO NEED TO MODEL!!!
Thank you in anticipation.