Your friend Jackie is in her spaceship and is traveling directly toward you at 0
ID: 1524142 • Letter: Y
Question
Your friend Jackie is in her spaceship and is traveling directly toward you at 0.9c. She is sitting in the middle of the spaceship inside which the only lights are a flashing green light at the front end of the ship and a flashing red light at its back end. At the instant that Jackie flies by you, you see the green and the red flashes occurring at exactly the same time. The only way that you would see the light occur at the same time, is if the green flash occurs first and red second. This is because at the instant that Jackie is flying past you, the green light is receding away from you, while the red is coming toward you. So, in Jackies’ frame of reference, the green flash occurs first, and red flash second. Now, suppose your friend Bob is traveling in a spaceship in the opposite direction from Jackie. Imagine that he is also precisely aligned with you and Jackie at the instant the two flashes of light occur (in your reference frame). According to Bob, which flash occurred first? [Extra: According to you, which flash illuminates Bob first?]
A) Bob will conclude that the red flash occurred before the green flash—the opposite of the order seen by Jackie, and not simultaneously as seen by you.
B) Bob will conclude that the green flash occurred before the red —the same as the order seen by Jackie, and not simultaneously as seen by you.
C) Bob will conclude that both flashes occur at the same time — not green and then red as seen by Jackie, also simultaneous as seen by you.
Explanation / Answer
bob will conclude that freen flash occured before the red - same order seen by Jackie and not simultaneously as seen by you.
reason is as bob is moving towards jackie, green light has lesser distance to reach him and red light has greater distance to reach him.
so as speed of light is constant, green light will reach first and then red light.
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