# The drag force

## Abbreviations

 cD Drag coefficient FD Drag force

## Explanation

The drag force FD is the component of the force FW in the direction opposite to that of the motion of the centre of gravity (see figure ). The force FW results from pressure differences at the bullet's surface, caused by the air, streaming against the moving body. In the case of the absence of yaw, the drag FD is the only component of the force FW .
The drag force is the most important aerodynamic force. Given the atmosphere conditions p,T,h, the reference area A and the momentary velocity vw, the drag force is completely determined by the the drag coefficient cD .