Exam-style question
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If two lightning strikes hit the ends of a moving train simultaneously in the train's rest frame, what happens in the ground frame?.
- A.They are simultaneous.
- B.The strike at the front occurs earlier.
- C.The strike at the rear occurs earlier.
- D.Both strikes are delayed.
Model answer
What a good answer should say
- The strike at the front occurs earlier.
Explanation
Why this works
Cause: The train's motion relative to the ground. Mechanism: The Lorentz transformation of time introduces a term proportional to the spatial separation and velocity, shifting the front event to an earlier time.
Effect: The front strike precedes the rear strike in the ground frame. Consequence: Ground observers disagree on the simultaneity of the strikes.
Common mistake
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