A bullet train moving in the $+x$ direction with $x$-velocity $\beta$ relative to the ground has lights on the roof of the head and tail cars that blink simultaneously in the train frame. The head car's light happens to be passing by an observer on the ground just as it blinks. The observer sees the light from the tail car at a different time, but after correcting for the light travel time from the tail car, the observer concludes that in the ground frame
A) The tail car's light blinked before the head car's light.}
B) The head car's light blinked before the tail car's light.
C) Both lights blinked simultaneously.
D) One cannot determine unambiguously which event occurs first in the ground frame.

Question

Quizplus · Accepted Answer

See figure 2 below. Note that events $T$ and $H$ both occur at $t^{\prime}=0$ in the train (Other) frame, and so both lie on the $x^{\prime}$ axis. If event $T$ defines $t=0$ in the train (Other) frame, then we can see that $H$ occurs after $T$ in the train frame because it is above the ground frame's $x$ axis.
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A Bullet Train Moving in The +x+x+x Direction With xxx -Velocity β\betaβ Relative to the Ground Has Lights on the Roof of -Velocity

A Bullet Train Moving in The $+x$ Direction With $x$ -Velocity $\beta$ Relative to the Ground Has Lights on the Roof of -Velocity