1) A planet revolves in an elliptical orbit around the sun. The semi-major and semi-minor axes are a and b. Then the square of time period T is directly proportional to A) $a^{3}$ B) $b^{3}$ C) $\left(\frac{a + b}{2}\right)^3$ D) $\left(\frac{a - b}{2}\right)^3$ Answer: Option AExplanation:The square of the period of the planet is directly proportional to the cube of the semi-major axis of the elliptical orbit. T2 $\propto$ a3
