Exam-style question
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Which of the following is a consequence of length contraction?.
- A.The speed of light appears different in different inertial frames
- B.The time interval between two events appears different in different inertial frames
- C.The length of a moving rod appears shorter to a stationary observer
- D.The mass of a moving particle appears larger to a stationary observer
Model answer
What a good answer should say
- The length of a moving rod appears shorter to a stationary observer
Explanation
Why this works
Formula/rule: Length contraction predicts L = L0 sqrt(1 - v^2/c^2). Substitution: For any v > 0, sqrt(1 - v^2/c^2) < 1, so L < L0.
Working: A stationary observer measures the contracted length. Answer: The length of a moving rod appears shorter to a stationary observer.
Units/conclusion: The measured length is in metres (m) and is reduced compared to the proper length.
Common mistake
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