Thread: Answer to the aeroplane problem on Facebook

If we are going to work with the badly worded version of the question at the start of this thread, then the answer is still, "Yes".

Since the discussion has turned into some sort of comprehension exercise, consider the following.

The question starts with the word, "Imagine". This suggests that we are expected to suspend disbelief and ignore what is actually possible in the real world. We can ignore the fact that it is unlikely that such a conveyor belt could exist. We just have to imagine it.

The conveyor belt is described as, "designed to exactly match the speed of the wheels". That raises the question of whether it is actually capable of doing what it was designed to do. Would the wording of the question allow for the assumption that the conveyor belt tries and fails to match the speed of the wheels? It also raises the question (as has already been mentioned) about which part of the wheel should be considered.

If the axle is the relevant part of the wheel, then if the axle and wheel are stationary, then the conveyor belt is also stationary.

If the conveyor belt is travelling in reverse at takeoff speed, then the axle, wheels and the plane will be moving forward at takeoff speed. At takeoff speed the plane can take off. There is no need for the conveyor belt to travel at warp speed.

Early on in this thread the claim was made that:
To move through the air the conveyor would need the aircraft to move along it.
But the question states that it can not.
Nothing in the question says that the conveyor prevents the plane from moving. It just mentions matching the speed of the wheels.

Making the wheels spin at twice the speed they normally do during takeoff does not stop the plane from moving.

"... Not sure just what is meant by "preasumptions", more likely it is just assumptions,or presumptions. It is a human failing to read or look at something and assume that it is what you are EXPECTING it to be, rather than what it actually is. It is how we are wired, rather than to do with brain power! ..."
Quote from Wise Farang...

I assume you're referring to 'expectation bias' ... or as it's sometimes called, 'Confirmation bias'

eg. It is morning and you have opened the hanger, and proceed to remove the little airplane the standard way by dragging it, expecting the magneto switches to be "OFF" ... so you don't look before taking hold of the prop...

Originally Posted by DiscoMick

If a man is all alone in the forest, a thousand kilometres from the nearest human, is he still wrong?

Depends on his marital status . . .

Originally Posted by Tombie

Work often places many of these testing type scenarios during project phases. It’s about understanding intent then arriving at a solution. Sometimes they are mutually exclusive

We have long understood 'Project Management' to be a Dark Art . . .

All this question is asking is can the 747 create enough thrust to overcome the friction of the wheels being, well basically having the brakes locked on as the belt and the wheels are moving at the same pace and the only way it will move forward is to drag the wheels as if they are not moving.
I think you would run out of tread before you get enough speed to achieve lift. Unless there is something that reduces friction between the tyres and belt.

Originally Posted by pjw

All this question is asking is can the 747 create enough thrust to overcome the friction of the wheels being, well basically having the brakes locked on as the belt and the wheels are moving at the same pace and the only way it will move forward is to drag the wheels as if they are not moving.
I think you would run out of tread before you get enough speed to achieve lift. Unless there is something that reduces friction between the tyres and belt.

Melting rubber. . .

If the engines on a massive rocket ignite and blast the rocket vertically upwards and at the same time the structure holding the rocket in place (by means of wheels that simply roll as the rocket moves) moves downwards at the same speed, will the rocket lift off?

Yes. Rocket engines are very powerful.

On further contemplation... the plane will take off... all that is needed is for the brakes to be applied the whole time, keeping them from spinning. The thrust will move the aircraft forward and since the belt matches the wheels (not rotating) will move forward to keep the same point in contact with the wheels, giving it the length it needs to gain enough speed to generate lift. Quite simple really when you think about it.