Two trains are moving with equal speed in opposite directions along two parallel railway tracks. If the wind is blowing with speed u along the track so that the relative velocities of the trains with respect to the wind are in the ratio 1 : 2, then the speed of each train must be

Options

A. 3u
B. 2u
C. 5u
D. 4u

Answer

A

Explanation

Let the speed of trains be v.
`therefore (v-u)/(v+u)=(1)/(2)`
or `2v-2u=v+u`
or `v=3u`