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 ?

Options

A. 750m
B. 1000m
C. 1250m
D. 2250m

Answer

C

Explanation

Relative velocity of A w.r.t. B –
` u_(BA) = 0`
Relative acceleration of A w.r.t B –
`a_(BA) = 1 - 0 = 1m//s^2`
Time taken to pass A = 50 se
`S_(BA) = u_(BA) t + 1/2 a_(BA)t^2`
`rArr S_(BA) = 0 + 1/2 xx 1 xx (50)^2 = 1250m` .