Question

4. Calculate the mean distance of a hypothetical planet from the sun which has a period of revolution of 100
years. You may take the distance between the sun and the earth as 1.5
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Answer 1

Answer:

Use Kepler's 3rd law: r^3/T^2 = constant. Compare with Earth: r = 1 AU and T = 1 year, which makes our constant = 1. Now r^3 = 1 AU x (300/365)^2 = 0.6755; hence r = 0.877 AU (=131.3 million km)