Kinetic friction is not constant but is an empirically derived approximation that varies under different conditions. Air friction increases with velocity, initially in a linear manner at lower speeds, and transitions to a quadratic relationship at higher speeds due to fluid dynamics complexities. Larger objects experience quadratic drag because they accelerate air molecules in front of them, resulting in a force proportional to the square of their velocity. Understanding these concepts requires a grasp of the underlying mathematics, as physics relies heavily on mathematical principles. For further clarification, resources like HyperPhysics can provide additional insights into friction and fluid dynamics.
