Question

Two trains 'A' and 'B' are moving on parallel tracks in opposite directions. The velocity of A' is twice that of B'. They take 18 seconds to cross each other. are the velocities of trains A and B ? Take length of train A as 240 m and that of B as 300 m.​

Answer 1

Train A velocity=2u m/s
Train B velocity =u m/s

240+300/18=30 m/s
3u=30 m/s
u=10 m/s

Therefore A=20 m/s
B=10 m/s
Hope this helps

Answer 2

Answer:

Velocity of train A is 72kmph

Velocity of train B is 36 kmph

Explanation:

As we know that

Velocity = displacement / time

Using this

Velocity of train A + velocity of train B =length of train A + length of train B

As velocity if train A is twice of velocity of train B ie

Va+Vb = la+lb/t

2Vb+Vb = 300+240/18

Vb = 10m/s

Converting m/s into kmph

10 X 3600/1000 = 36 kmph

Velocity of train B is 36 kmph

Velocity of train A is twice of B

Ie 36x2 = 72 kmph