Answer to the aeroplane problem on Facebook

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Originally Posted by Tombie

The moment the jets provided thrust and the wheel tried to roll, the belt instantly matches it (1st impossibility)... this immediately goes into melt down as the PLC ramps to the belt to light speed (2nd impossibility).

The requirement is that the wheels stay in place to comply with the question preassumptions (3rd impossibility)

See? To meet the question criteria it can not happen.

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Let me punch a hole in your theory. For the wheels to stay in place, you must be using the velocity of the top of the wheel for the velocity of the conveyor to be the same speed in the opposite direction. In this case, the plane will not take off.
If you used the velocity of the bottom of the wheel, the wheel would just be doing a big skid with the difference in velocity being twice that of the velocity of the conveyor. In this case, the plane will not take off.
The question specifically mentions the speed of the wheel. It makes no reference to any particular part of the wheel, just the wheel. If the wheel moves forward at Xm/s, the conveyor moves in the opposite direction at Xm/s with the difference being 2Xm/s. In this case the plane may or may not take off depending on further conditions not given in the question.

Basically, the question is nonsensical.

If a tree falls in a forest and no one is around to hear it, does it make a sound?

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Originally Posted by Eevo

If a tree falls in a forest and no one is around to hear it, does it make a sound?

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Only if the conveyor belt is running.

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Originally Posted by Tombie

Not this one Billy... this is the Comprehension one.
If all conditions are to be met it is impossible.

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Agreed: I suppose I should have read the question. I assume it was the original one.
However; had you not pointed it out as a comprehension question I still would have said the bloody thing would take off.
It's a commendable level of comprehension you have Mike, if you can put aside all your knowledge and prejudice and just focus on the question. I for one, am often trapped by these ones.

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Originally Posted by cuppabillytea

Agreed: I suppose I should have read the question. I assume it was the original one.
However; had you not pointed it out as a comprehension question I still would have said the bloody thing would take off.
It's a commendable level of comprehension you have Mike, if you can put aside all your knowledge and prejudice and just focus on the question. I for one, am often trapped by these ones.

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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 [emoji6]

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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 [emoji6]

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I write questions for students to answer. Getting them to focus on what the question actually asked them is the big challenge. Their brains run off at tangents and don't focus on the key words and phrases.
Some of the posts in this thread seem to have ignored what the question actually asked, often in very imaginative ways, maybe because the person has other knowledge they think is relevant, but if it's not in the question its irrelevant.
The way I understand this question, the wings can't get any uplift under the conditions set in the question, so no takeoff is possible. My engineering student son reached the same conclusion.

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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 [emoji6]

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Not sure if I should bother with this anymore but having nothing else better to do here goes!

The composition of the original question is more to do with semantics, than anything else.

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!

https://glosbe.com/en/en/preassumptions

In this case I suspect that many people are "assuming"that the aircraft engines are running, whereas it makes no mention about the engines, or anything about any thrust on the airframe.

During my time working on Offshore Oil Rigs and Drillships over more than 30 years, I attended many training and safety courses designed to highlight this human failing. The most simplest of training situations were very often interpreted in some dangerous ways by what should of been some of the most qualified participants.The very reason the courses were held in the first place!

I also flew helicopters commercially, and here again "assumptions" can and do lead to accidents and quite often fatalities. As an example: a couple of years ago a police air wing in the US destroyed two helicopters when one of them ran into one on the ground while coming in to land. The pilot of the landing aircraft assumed that the one on the ground, with rotors turning, was parked on a clearly marked spot, where it "always was". In fact, the groundcrew had pushed the one on the ground out of the hanger and set it down outside of the marked spot by several feet in the direction of the adjacent parking spot. The incoming pilot had around 15,000 hours experience, so could not be accused of being a novice! Nobody was killed in this case, just injured.

At one time part of my job was investigating equipment failures and also writing maintenance procedures. I cannot remember how many times while investigating an occurrence or failure, the response to a question concerning why something had not been spotted long before it had failed because of something obvious, the answer would be:"but it has always been like that"!

Sorry to ramble on! :twobeers:

Reminds me of the time a Dreamliner was sent on a promotional tour and landed at Bangkok Airport. As it taxied and turned the end of the wing of this shiny new plane slowly sliced open the end of a hangar. Apparently someone had forgotten to check the length of the wings on the new plane, which were slightly longer, and had assumed there was enough room.

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Originally Posted by DiscoMick

I write questions for students to answer. Getting them to focus on what the question actually asked them is the big challenge. Their brains run off at tangents and don't focus on the key words and phrases.
Some of the posts in this thread seem to have ignored what the question actually asked, often in very imaginative ways, maybe because the person has other knowledge they think is relevant, but if it's not in the question its irrelevant.
The way I understand this question, the wings can't get any uplift under the conditions set in the question, so no takeoff is possible. My engineering student son reached the same conclusion.

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A wife asks her husband, a software engineer...
"Could you please go shopping for me and buy one carton of milk, and if they have eggs, get 6!" A short time later the husband comes back with 6 cartons of milk. The wife asks him, "Why the hell did you buy 6 cartons of milk?" He replied, "They had eggs."

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Originally Posted by Eevo

If a tree falls in a forest and no one is around to hear it, does it make a sound?

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Silence of the Tree,s . :woot: