The classical physics works on the Newton's laws of motion. It is applicable on heavenly bodies which are governed by the gravitational force. On the other hand, Quantum Physics is applicable for very low mass and sized bodies like electron, protons etc. The classical physics would accurately describe the motion of satellite moving with speed 7500 m/s using the following formula:
where G is the gravitational constant, M is the mass of the planet and v is the orbital speed. Then radius of the orbit can be described by this formula.