Plane on a treadmill

I want to one up on Cecil’s explanation on why this question confuses so many people and why the answer really is so simple…that the plane DOES take off.

First, in Cecil’s column she mentions, “Relatively speaking…”…yes indeed, relativity is what it’s all about.

The question puts the reader’s mind in the perspective of the PLANE relative to the CONVEYOR BELT, while in reality both the plane AND the conveyor belt are moving relative to the rest of the universe.

The difference between the two ways of thinking is this;

a)If the plane was moving only relative to the conveyor belt, the reader cannot envision the plane is actually also moving forward relative to everything else. In short, he only sees the plane standing still relative to everything else, and the plane’s wheels and the conveyor belt moving around and around.

This would make sense mathematically too since all the movement needs to be in the wheels and the conveyor belt.

b)If the movement of both the plane and the conveyor belt was relative to the viewer standing still in the eternal mass of the rest of the universe, then all of a sudden the plane’s “forward movement” is through the rest of the universe and the conveyor moving backwards is also an equal speed through the rest of the universe but in the other direction (at the top of the conveyor belt at least…) Then it makes sense that no matter how fast the conveyor belt is moving back against the plane it only needs to be going as fast as the plane’s take off velocity through the air mass (which is part of “the rest of the universe”) in the other direction, which can be as low as 40 mph for some small light aircraft.

Then the question becomes merely “Can we make wheels that roll in 80 mph easily enough to allow an ultra light aircraft to take off in 40mph true airspeed?”

Ummm…what? The question is a hypothetical. Your analysis of the two different cases seems to be correct,but you can’t claim that the question implies one thing and “reality” is different. There is no “real” event the question refers to.

Cecil n’est pas une Cecile.

Haha, bad grammar is the American way. Cecil est Dieu.

The question is hypothetical, but it is based on the possible applications of existing technology.

A plane has enough thrust to take off in a normal situation.

The question is whether it can also take off if it was placed in a different, hypothetical situation.