Constant GRAVITATIONAL_CONSTANT 

pub const GRAVITATIONAL_CONSTANT: f64 = 6.674_30e-11; // 6.6742999999999994E-11f64

Newtonian constant of gravitation, in cubic meters per kilogram second squared.

This crate keeps the value locally as a convenience for gravity-specific helpers. Broader physical constants belong in the top-level use-constants set.