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JEE Main 2023 (24 Jan, Shift 2) · Kepler's Laws & Planetary Motion

Kepler's Laws & Planetary Motion question from JEE Main 2023 (24 Jan, Shift 2)

Q10JEE Main 2023 · 24 JAN · SHIFT 2Medium

Kepler's Laws & Planetary Motion

If the distance of the earth from Sun is 1.5 ×\times 1066 km. Then the distance of an imaginary planet from Sun, if its period of revolution is 2.83 years is:

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Answer: (d)

  1. Kepler's third law: T2∝r3T^2 \propto r^3, so r2=r1(T2T1)2/3r_2 = r_1 \left(\frac{T_2}{T_1}\right)^{2/3}.
  2. Earth: T1=1T_1 = 1 year, r1=1.5×106r_1 = 1.5 \times 10^{6} km (value as given).
  3. (2.83)2≈8\left(2.83\right)^{2} \approx 8, so (2.83)2/3=81/3=2(2.83)^{2/3} = 8^{1/3} = 2.
  4. r2=2×1.5×106=3×106r_2 = 2 \times 1.5 \times 10^{6} = 3 \times 10^{6} km
  5. So the answer is (d) 3×1063 \times 10^{6} km.
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