play phryzby with physics

Q. In accordance with the Bohr's model, what is the quantum number that characterises the earth's revolution around the sun in an orbit of radius 1.5 × 10¹¹ m with orbital speed 3 × 10⁴ m/s? (Mass of earth = 6.0 × 10²⁴ kg.) expects 2.6 × 10⁷⁴