Explanation:
G is the universal constant of gravitation, approximately 6.67×10⁻¹¹ m³/kg/s².
g is the acceleration due to gravity. It's defined by the universal law of gravity as:
g = MG / r²
where M is the mass of the planet and r is the distance from the planet's center to the object.
Near the surface of the Earth, g is approximately 9.8 m/s².