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 ` (A) , what was the originaldistance between them ?

Explanation

For train ` A, u= 72 h^(-1) = ( 72 xx 1000)/( 60 xx 60) =20 mS^(-10 , t = 50 s, t= 50 , a =0, S=S_A`
As. ` S= ut = 1/2 at^2 :. `S_A` = `20 xx 50 + 1/2 xx 0 xx 50^2 = 1000 m`
For train ` B` , u= 72 km s^(-10 = 20 ms^(-1) , a= 1 m//s^2 , t = 50 s, S= S_B`
As, ` S =ut = 1/2 at^2` :. S_B = 20 xx 50 = 1/2 xx 1 xx 50^2 = 22 50 = S-B`
Taking the guard of the (B) in the last copartment of the train (B), it follows that original distance between the two trains = length of train ` A + length of train ` B= S_B - S_A`
or orginal isanc ebetween the two trains ` + 400 + 400 = 2250 - 1000 = 1250`
or original distance between the two trains `= 1250 =- 800 = 450 m`.