Question

A. Let the period of revolution of a planet
at a distance R from a star be T. Prove
that if it was at a distance of 2R from
the star, its period of revolution will be
V8 T.
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Answer 1

. According to Kepler's third law, The square of orbital period of revolution T of a planet around a star is directly proportional to the cube of the mean distance R of the planet from the star. Thus, for a planet, at a distance of 2R from the star, its period of revolution will be √8 T.