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.
Drag is the aerodynamic force that opposes an aircraft's motion through the air. Drag is generated by every part of the airplane (even the engines!). How is drag generated? Drag is a mechanical force. It is generated by the interaction and contact of a solid body with a fluid (liquid or gas).