Exam-style question
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If a spaceship travels at 0.6c relative to Earth, how does its clock compare to Earth's clock?.
- A.It ticks 1.25 times faster.
- B.It ticks 1.25 times slower.
- C.It ticks at the same rate.
- D.It ticks 0.8 times slower.
Model answer
What a good answer should say
- It ticks 1.25 times slower.
Explanation
Why this works
Formula: Δt = γ Δτ. Substitution: v = 0.6c → γ = 1/√(1–0.36) ≈ 1.25.
Working: Δt = 1.25 Δτ. Answer: the spaceship’s clock takes 1.25 times longer to tick one second, so it runs slower.
Units/conclusion: The spaceship’s clock runs 1.25 times slower than Earth’s clock.
Common mistake
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