Exam-style question
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In which direction does length contraction occur?.
- A.Only along the direction of relative motion
- B.Only perpendicular to relative motion
- C.Both directions equally
- D.Neither direction
Model answer
What a good answer should say
- Only along the direction of relative motion
Explanation
Why this works
Formula/rule: Length contraction applies only to dimensions parallel to the relative velocity: L = L0 sqrt(1 - v^2/c^2). Substitution: The Lorentz factor γ = 1/sqrt(1 - v^2/c^2) only modifies lengths along the motion.
Working: Perpendicular dimensions are unaffected (L⊥ = L0). Answer: Only along the direction of relative motion.
Units/conclusion: The effect is a reduction in metres (m) along the motion axis.
Common mistake
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