Work out air resistance at speed instantly with clear inputs, formula shown and shareable results.
Drag force is dynamic pressure times drag area: half rho v squared times Cd times A. Force rises with the square of speed and power with the cube, which is the fundamental reason motorway fuel consumption climbs so steeply above 100 km/h.
Aerodynamic drag
F = 0.5 x rho x v^2 x Cd x A; P = F x v
Force scales with v squared and power with v cubed. 1.1 cubed is 1.33, so a tenth more speed needs a third more power.
Yes. At altitude or on a hot day density falls, reducing drag by a few percent — one reason speed records are set at high altitude.