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

Question

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 (A)  3u  (B)  2u  (C)  5u  (D)  4u

Tardigrade Admin · Accepted Answer

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

Q. 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

$3 u$

$2 u$

$5 u$

$4 u$

$u$

Let the speed of trains be v.
$∴$ $\frac{v - u}{v + u} = \frac{1}{2}$
or $2 v - 2 u = v + u$
or $v = 3 u$

Q. 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

3u

2u

5u

4u

u

Let the speed of trains be v. ∴ v+uv−u​=21​ or 2v−2u=v+u or v=3u