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Anna is on a railroad flatcar moving at 0.6c relative to Bob. (Their clocks read 0 as Anna’s center of mass passes Bob’s.) Anna’s arm is outstretched in the direction the flatcar moves, and in her hand is a flashbulb. According to the wristwatch on Anna’s hand, the flashbulb goes off at 100 ns. The time of this event according to Bob differs by 27 ns. (a) Is it earlier or later than 100 ns? (b) How long is Anna’s arm (i.e., from her hand to her center of mass)?
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Modern Physics
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