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Question 30638

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Circular Motion: Time Period — Planet MCQ

Solve this quality-checked JEE multiple-choice question, then review the correct answer and explanation.

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Time Period — PlanetMediumQuestion 30638

Question

A planet orbits at radius r with period T. Another planet at 4r has period:

A
2T
B
4T
C
8T
Correct
D
16T

Correct answer

8T

Explanation

By Kepler's 3rd law: T² ∝ r³. (T₂/T₁)² = (4r/r)³ = 64 → T₂/T₁ = 8 → T₂ = 8T.

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