[sanddrag]

Originally Posted by EddieMcD

I just have one question about the treadmill: is the runway moving itself (to match the plane's forward speed) via motors, or is it the plane's force against the runway causing it to move?

The plane would not be able to move the runway in the opposite direction unless the wheels were driven (like an automobile). So, I'm assuming the runway has some really freaking huge motor driving it in a continuous loop like a treadmill.

Now, for anyone else who doesn't get why the plane does take off, draw your free body diagrams You are mingling your separate forces into two different systems that have very little to do with each other. Isolate the system, and then determine the forces.