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.
Vocabulary/Definitions. 1  Acceleration: A change in direction, or speeding up or slowing down. 2  Aeronautical engineer: A person who studies the forces involved in flight. 3  Drag: The force that slows an airplane or parachute down. 4  Force: Something that acts from the outside to push or pull an object. For example, an adult pulling a child in a wagon exerts a force upon the wagon. Lift: The force that pushes an airplane up into the air. Lift is caused by the shape of an airplane's wings.