Aerodynamics is the way objects air. the rules of aerodynamics anything that moves through air is affected by aerodynamics,from a rocket blasting off, to a kite flying. since the are surrounded by air, even cars are affected by aerodynamics. 
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I dint understand.. The question is how is aerodynamics used
Aerodynamics is the study of forces and the resulting motion of objects through the air.    

Studying the motion of air around an object allows us to measure the forces of lift, which allows an aircraft to overcome gravity, and drag, which is the resistance an aircraft “feels” as it moves through the air. Everything moving through the air (including airplanes, rockets, and birds) is affected by aerodynamics.