The "Plane on a Treadmill" Question

[tw]

Originally Posted by glatt

The question was written from the point of view of an observer, right? That observer is the one doing the measuring of the forward speed. It's forward speed relative to the observer.

That observer could be:
1. standing on the ground,
2. floating in the air,
3. standing on the treadmill, or
4. sitting in the plane

We simply do the answer as demonstrated in post 152 and then change the answer to that 'observers' reference.

We do same thing with electricity. Which is ground? Earth? Breaker box? Computer motherboard? Any one can be ground. We can define any point as the reference point. We select any reference point only to make the problem easier to solve. Same applies to this problem.

We have three possible 'grounds' - points of reference. Four if we complicate the problem by considering an observer. The observer is completely unnecessary to the question - airspeed - velocity between airplane and air.

Air is a perfect reference point because a clearly defined relationship exists between air and the plane.

When the plane's engines throttle up, ...

And we have a known relationship between air and the runway or treadmill. Break a problem into parts. We do all numbers relative to air AND therefore have a simple answer.

Obviously - and this is just too simple for all the speculation - obviously -As the engines throttle up, the plane does take off whether it is on a runway or on a treadmill. Obviously because what the treadmill does is completely irrelevant to (independent of) airplane and air. Obviously plane's airspeed only involves a relationship between air and airplane. Obviously observer’s location and what treadmill does are completely irrelevant. Obviously wheels make that treadmill movement completely separate of (independent - not connected to) airplane and air. Obviously location of observer is completely separate from (independent of) airplane and air.

It is quite scary that so many cannot grasp these obvious and simple relationships. Some of these replies are making me feel like a genius. That scares me.