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
A) $3u$
B) $2u$
C) $5u$
D) $4u$
Explanation
(a) Let the speed of trains be $x$
$\therefore\frac{x - u}{x + u} = \frac{1}{2} \Rightarrow 2x - 2u = x + u \Rightarrow x = 3u$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.