Question

Two railway tracks are parallel to west-east direction. Along the track, train A moves with a speed of $54km/h$ from west to east while along the second track B moves with a speed of $90km/h$ from east to west. Find (i) the relative velocity of B w.r.t A and (ii) relative velocity of ground w.r.t B

Answer 1

$\left(i\right)$ Relative velocity of B w.r.t A= Sum of speeds of trains

$=54+90$

$=144kmph$

$\left(ii\right)$Relative velocity of B w.r.t Ground(G)$=v_{B/G}=-90kmph$

$v_G=0$

Relative velocity of ground(G) w.r.t B $=v_{G/B}=v_G-v_{B/G}$

$v_{G/B}=0-(-90)$

$v_{G/B}=90kmph$