Which equation represents the relationship between drag and airspeed?

The relationship between drag and airspeed is defined by aerodynamics principles, specifically through the drag equation, where drag is proportional to the square of the airspeed. This means that as the airspeed of an object increases, the drag force acting upon it increases at a rate that is not linear but rather quadratic.

When the velocity (airspeed) doubles, for instance, the drag force does not simply double; it actually quadruples because drag is dependent on the square of the velocity. This phenomenon is due to the physics of fluid dynamics, where the amount of air resistance that an object encounters increases significantly as its speed increases.

Understanding this quadratic relationship is crucial for pilots and engineers alike, as it affects aircraft performance, fuel efficiency, and overall safety. Therefore, the equation that best represents this relationship is the one where drag is equal to airspeed squared, capturing the essence of how drag increases with higher speeds.