Question

what physics principles are applied to airplanes

Answer 1

Bernoulli built his work in the study of how fluids
behave when they are in motion. Air, like water, is a fluid; however, unlike water, which is a liquid, air is a gaseous substance. Air is considered a fluid because it flows and can take on different shapes. Bernoulli asserted that as a fluid moves faster, it produces less pressure, and conversely, slower moving fluids produce greater pressure.
We are able to explain how lift is generated for an airplane by gaining an understanding of the forces at work on an airplane and what principles guide those forces. First, it takes thrust to get the airplane moving - Newton’s first law at work. This law states that an object at rest remains at rest while an object in motion remains in motion, unless acted upon by an external force.Then because of the shape of an airplane’s wing, called an airfoil, the air into which the airplane flies is split at the wing passing above and below the wing at different speeds so that the air will reach the same endpoint along the wing at the same time.
In general, the wing’s upper surface is curved
so that the air rushing over the top of the wing speeds up and stretches out, which decreases
the air pressure above the wing. In contrast, the air flowing below the wing moves in a straighter line, thus its speed and pressure remain about the same. Since high pressure always moves toward low pressure, the air below the wing pushes upward toward the air above the wing. The wing, in the middle, is then “lifted” by the force of the air perpendicular to the wing. The faster an airplane moves, the more lift there is. When the force of lift is greater than the force of gravity,
the airplane is able to fly, and because of thrust, the airplane is able to move forward in flight. According to Newton’s third law of motion,
the action of the wings moving through the air creates lift.