Now let's look at flight as a function.

We'll start with something familiar, and think about how an airplane works.

There are two forces that a plane must overcome to fly.

A plane must overcome its own weight.

It must also act against air resistance that opposes forward movement.

This force is known as drag.

There are two forces generated by the plane to overcome weight and drag.

An airplane’s engines generate thrust to stay aloft and move.

 

As thrust moves the plane forward, air flowing past the wing generates an upward force known as lift.

 

The air pressure on the underside of the wing is greater than on the top of the wing.

This difference in pressure generates lift.