Two trains A and B of length 400 m each are moving on two parallel tracks with a uniform speed of `72 km h^(-1)` in the same direction, with A ahead of B. The dirver of B decides to overtake A and accelerates by `1 ms^(-2)`. If after 50s, the guard of B just brushed past the driver of A, what was the original distance between them ?

Explanation

Let s= distance between the trains initially
Velocity of trains initially
velocity of train B w.r.t. A is zero, acceleration of train B w.r.t. A a`=1 ms^(-2)`
than distance `s=ut+(1)/(2)at^(2)=0+(1)/(2)xx(50)^(2)=1250m`