If an object is in the steady air (not wind) is it subject to an aerodynamic force? And if an object moves in the air, is there any aerodynamic force on it? What is the most important parameter in aerodynamic force?

Analyze the factors that influence the choice between the following pairs of processes to make the products indicated: i) sand casting versus die casting of an electric-motor housing ii) thread rolling versus machining of a bolt for high-strength application. (co3/c5)