Plane
When talking about flight and aeronautics, the first thing that most people think of, is planes. When we talk about planes in a scientific sense, we generally talk about the aerodynamic principles of lift, drag, weight, and thrust. Lift is the force that moves something up, the opposite of weight. Weight is the force generated by the earth's gravitational pull on the object. Thrust is the force which moves a plane forward through the air, and it's the opposite of drag. Drag is what opposes a plane's motion through the air.