There is a giant, 10 mile long stetch of runway with a 747 on the middle of it. The runway, however, is specially designed to move, much in the same way that a treadmill will move, in the opposite direction of the plane. Secondly, the treadmill is attached to a computer which will match the acceleration of the plane exactly and constantly, in the opposite direction.
What is the result of this experiment? Does the plane ever take off?
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Anonymous2006-11-02 18:03
Ok, since it seems people here are still in second grade, I'll use a childish analogy to explain my point.
You have a treadmill. Normal, simple treadmill.
Now, put a skateboard on the treadmill. Place your hand on top of it, holding it solidly.
Again the computer is attached so the speed of the treadmill is exactly the same as the speed of the skateboard, in the opposite direction.
Hold this all in your head... good...
Now, push the skateboard forward at 1 MPH. The computer instantly sends the treadmill backwards at 1 MPH.
But you can still easily pull the skateboard foward with your hand! The skateboard is moving forward at 1 MPH, the treadmill is moving backwards at 1 MPH, and the wheels of the skateboard are moving at 2 MPH (the difference).
Here's an even more obvious one. A treadmill is moving backwards at 20 MPH. You slowly set a skateboard on it, but hold it in place. The skateboard is moving at 0 MPH, the wheels at 20 MPH, and the treadmill at 20 MPH backwards.
You can still imagine moving the skateboard forward along that treadmill with your hand at 1 MPH. Now, the skateboard is moving at 1 MPH, the wheels at 21 MPH, the treadmill at 20 MPH.
The engines on the plane simply replace the force your hand is exerting on the skateboard. It will move forward and take off as normal.