# i tried to answer this question myself but i couldn't.i would like to get a detailed explanation.Two trains started from point A and B in opposite direction and moves with different velocities.They...

i tried to answer this question myself but i couldn't.i would like to get a detailed explanation.

Two trains started from point A and B in opposite direction and moves with different velocities.They reaches their destination in 2 h and 1 h after crossing each other.What is the ratio of velocities of the train?

mlsiasebs | College Teacher | (Level 1) Associate Educator

Posted on

If we assume that the distance travelled after they cross each other is the same, then we can set up a ratio.  We know that

`v=d/t` for both trains

and that can be rearranged to

d = v*t

If the distance is the same for both trains

d(A) = d(B)

then the following must also be true

v(A)*t(A) = v(B)*t(B)

Where v and t are the velocity and time of each train (designated by A or B).

We can then rearrange that to find

`(v(A))/(v(B)) = (t(B))/(t(A))`

Since we know that the time for train A is hour and for train B is 2 hours (assuming that because of the way they are written in the problem), then we know that

`(v(A))/(v(B))=2/1`

So Train A is travelling twice as fast as Train B.