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Question 30765
JEE Physics · Hard

Gravitation: JEE — Angular Momentum Orbit MCQ

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

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JEE — Angular Momentum OrbitHardQuestion 30765

Question

A planet moves in an ellipse. At aphelion (distance r_a, speed v_a) and perihelion (r_p, v_p). Which relation holds?
  1. A
    v_a/v_p = r_p/r_a
  2. B
    v_a r_a = v_p r_p
    Correct
  3. C
    v_a²r_a = v_p²r_p
  4. D
    v_a = v_p

Correct answer

v_a r_a = v_p r_p

Explanation

Conservation of angular momentum: L = mv_a r_a = mv_p r_p → v_a r_a = v_p r_p. Since r_a > r_p, v_a < v_p (slower at aphelion).

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