quadratic_drag_projectile: Numerical investigation of projectile motion with quadratic drag

Python simulation code for the paper "Numerical investigation of projectile motion with quadratic drag: A computational approach for undergraduate physics teaching" (European Journal of Physics). The code implements dimensional and nondimensional formulations of projectile motion with quadratic air resistance, providing: (1) Forward Euler and fourth-order Runge-Kutta (RK4) numerical integrators; (2) step-size convergence analysis with relative error metrics; (3) parameter sweeps over launch angle, initial speed, mass, and drag coefficient; (4) data collapse verification of nondimensional scaling; (5) reachable region and hit envelope construction; (6) comparison with vacuum (no-drag) trajectories. All simulations use identical physical parameters when comparing numerical schemes, ensuring that observed differences arise from algorithmic effects rather than from changes in launch conditions.