1 AFib reduces the ability of the atria to pump blood into the ventricles, and usually causes the heart to beat too rapidly. 2  One-half million new cases of atrial fibrillation are diagnosed every year in the U.S., and billions of dollars are spent annually on its diagnosis and treatment.
noun, (used with a singular verb) 1. the branch of mechanics that deals with the motion of air and other gases and with the effects of such motion on bodies in the medium. Compare aerostatics (def 1). Origin of aerodynamics.
Sometimes, the speed of an object is described relative to the speed of something else; preferably some physical phenomena. 1  Aerodynamics is the study of moving air and how objects interact with it. 2  In this field, the speed of an object is often measured relative to the speed of sound.