Gravity is constant, with positive y upward. Without air resistance, every object has the same acceleration.
Air resistance adds drag opposite to the velocity. The model uses still air and a constant drag coefficient for every ball:
Air density ρ = 1.225 kg/m³; CD = 0.47; cross-sectional area A = πd²/4. Objects have representative fixed masses and diameters, shown beside the selector. Their size and mass both affect drag acceleration.
This is a simplified ball model: no wind, lift, spin or buoyancy. The same drag coefficient lets you compare the chosen sizes and masses without changing the surface model.
Flight ends at first contact with y = 0. Values at landing are just before impact. Changing launch settings prepares a new shot; completed or partial earlier paths can be retained for comparison.