JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Gravitation

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Every planet revolves around the sun in an elliptical orbit :

A. The force acting on a planet is inversely proportional to square of distance from sun.

B. Force acting on planet is inversely proportional to product of the masses of the planet and the sun

C. The centripetal force acting on the planet is directed away from the sun.

D. The square of time period of revolution of planet around sun is directly proportional to cube of semi-major axis of elliptical orbit.

Choose the correct answer from the options given below :
  1. (A)A and D only✓ Correct
  2. (B)C and D only
  3. (C)B and C only
  4. (D)A and C only

Answer: (A)

Solution

The sun's pull on a planet is , which falls off as the inverse square of the distance, so that statement is sound; it grows with the product of the masses rather than falling with it, so the claim of inverse proportionality to the masses is wrong. The force that curves the orbit points toward the sun, not away from it, so that statement is wrong too. Kepler's third law, , is correct. Only the inverse-square statement and the period--semi-major-axis statement are right.

JEE Main · 2023 · 25 Jan 2023 · Shift 2 · Single correct option

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