Drag equation by experiment. Of particular importance is the formula_8 dependence on flow velocity, meaning that fluid drag increases with the square of flow velocity. When flow velocity is doubled, for example, not only does the fluid strike with twice the flow velocity, but twice the mass of fluid strikes per second. Therefore, the change of momentum per second is multiplied by four. Force is equivalent to the change of momentum divided by time. This is in contrast with solid-on-solid friction, which generally has very little flow velocity dependence. The drag force can also be specified as, formula_9 where, "P" is pressure
Velocity air meter of the air - and the ECU cannot distinguish, for a given door angle, whether the air is less dense but traveling faster or whether the air is denser but traveling more slowly. Therefore air velocity must be corrected for air density (temperature and barometric pressure) in order to reflect air mass (actual number of air molecules entering the engine per unit of time). Velocity air meters from Bosch have been commonly used on systems such as older Bosch L-Jetronic and as a part of many factory systems, though they now have mostly been superseded by mass airflow sensors which