Video narration
Does doubling your speed merely double the resistance pushing against you? When you coast a bicycle through air, drag force pushes opposite your motion, slowing you down. But drag has no single speed rule. Linear drag is proportional to speed: double speed, double drag. Quadratic drag is proportional to speed squared: double speed, and drag becomes four times larger, because two squared is four. The direction stays opposite motion; the minus sign in a vector equation simply records that. Which model fits depends on the flow around the object-not speed alone. The coefficient depends on the object, its shape, the fluid, and the conditions. Linear drag is common in slow, viscous flow. Quadratic drag describes many objects moving through air at ordinary higher speeds. No. Linear drag doubles with speed; quadratic drag quadruples, when the flow makes that model appropriate.