The "Plane on a Treadmill" Question

[xoxoxoBruce]

Jet engines don't push against the air, they push against the plane. The plane will be pushed forward until it reaches takeoff velocity, no matter what speed the wheels are turning. All they do is keep the plane from dragging on the ground. Planes take off from runways that are moving at 1000 mph, under them, every day.

Originally Posted by Undertoad

The answer to why manholes are round? Because men are round. Duh

So a man can tip open a lid that would be to heavy to lift.