Question

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 driver of B decides to overtake A and accelerates by 1 m s¯². If after 50 s, the guard of B just brushes past the driver of A, what was the original distance between them ?

Answer 1

Given, the length of the train A and B is 400 m each.

Both the trains are moving in the same direction with the same speed, so the relative velocity of both train is zero, that is, v AB = v BA =0

Let s be the original distance between the trains, a be the acceleration of the train and t be the time period.

The second equation of motion is,

s= u AB t+ 1 2 a t 2

Substitute the value in the above expression.

s=0×t+ 1 2 ×1× ( 50 ) 2 =1250 m

Thus, the original distance between the driver of train A and guard of train B is 1250 m .