Plane

[Golf is fun]

Yes, but you can't do this and stick to the rules of the puzzle.

Position yourself so you can reach the travelator but you are not on it yourself.

Hold the dinky car still (relative to yourself) on the travelator - what are the wheels doing?

Now push the dinky car in the same direction as the travelator at exactly the same speed as the travelator - what are the wheels doing? What is the dinky car doing relative to you or any fixed object not on the travelator?

The only difference in this experiment is the travelator speed is not changing and you're adjusting the car speed to stop the wheels - it's reversed from the question scenario where the plane speed is changing but you're adjusting the conveyor to stop the wheels, but the net outcome is the same.

 

[Deleted member 36735]

To sumarise the puzzle as I see it - assuming the puzzle is written so that jet and treadmill travel in the same direction (which I believe it is) then the jet takes off as normal, the only interesting thing being that the wheels don't rotate (effectively the runway is travelling at the same speed as the jet).

I have acknowledged that the description of "counteracting" can mean that and I have no issue with that interpretation.

A lot of the confusion I think comes from considering what happens if jet and conveyor travel in opposite direction. In almost all scenarios, the jet takes off normally.

There is no normal scenario in the puzzle.

The only situation where there is an issue is if the wording of the problem forces the conveyor to exactly match wheelspeed.

That is exactly the scenario.

For the reasons explained, this is not feasible.

But you can't create reasons to explain why this can't happen, the scenario says it does happen so that is all we have to work with. It's not about real life, it's simply interpreting the scenario as written.

The only scenario in which conveyor and wheelspeed are exactly matched is if the jet is stationary.

Not true. As you previously mentioned, if they are going in opposite directions at the same speed this matches the criteria.

Since there is nothing to stop the jet moving, the conveyor will always be slower than the wheels, which means it will always be accelerating, which means it will likely break very quickly - this is however not the scenario as layed out in the OP.

As you say, that is not the scenario so why muddy the waters any more?

I think some people aren't differentiating between what they think or know will happen in real life versus the strict wording of the puzzle.

 

[Deleted member 35927]

No, I've given numerous lengthy posts over the past few days that have done my best to describe my thought process as best I can whilst also acknowledging the other point of the argument.

What you have done though is simply deny anyone else's point with absolutely no logic or cohesive points of your own.
You continue to use laughing emojis and reply along the lines of "I haven't got a clue what you're on about ".
Your own points are the least logical of everyone's, all you have done is criticise without offering any type of intelligent input.
Irrelevant of which point of view they have, Rich A, Swango, Voyager et al have all written their points logically and have tried to explain themselves rationally, unlike you.

"Because it's science" doesn't cut it.

Nothing could be further from the truth, when you're pressed to give answers based on science fact you're unable to and simply ignore them and quote but it's the rules. other than that your constant fall back is the exact type of reply your just given.
I suppose it beats your plane that stops dead if we roll this in reverse

 

[Golf is fun]

But you can't create reasons to explain why this can't happen, the scenario says it does happen so that is all we have to work with. It's not about real life, it's simply interpreting the scenario as written.

The thing with this statement is that it's not physically (as in the laws of physics) possible. If you insist on sticking to that point the laws of physics no longer apply so we might as well accept every answer to be both valid and invalid depending on which unknown random rules we are making up.

The answer may as well be the plane takes off because magic beans, or the plane both takes off and doesn't take off because reasons, or the plane takes off because it is in the third dimension where everything takes off, if we're abandoning physics we may as well abandon any other logic too.

 

[Deleted member 35927]

The thing with this statement is that it's not physically (as in the laws of physics) possible. If you insist on sticking to that point the laws of physics no longer apply so we might as well accept every answer to be both valid and invalid depending on which unknown random rules we are making up.

The answer may as well be the plane takes off because magic beans, or the plane both takes off and doesn't take off because reasons, or the plane takes off because it is in the third dimension where everything takes off, if we're abandoning physics we may as well abandon any other logic too.

Exactly this. All the answers I have seen that keep the plane on the belt also defy the laws of physics.

 

[Bobski]

I have acknowledged that the description of "counteracting" can mean that and I have no issue with that interpretation.

There is no normal scenario in the puzzle.

That is exactly the scenario.

But you can't create reasons to explain why this can't happen, the scenario says it does happen so that is all we have to work with. It's not about real life, it's simply interpreting the scenario as written.

Not true. As you previously mentioned, if they are going in opposite directions at the same speed this matches the criteria.


As you say, that is not the scenario so why muddy the waters any more?

I think some people aren't differentiating between what they think or know will happen in real life versus the strict wording of the puzzle.

The scenario in the OP I believe is that the conveyor moves to counteract the rotation of the wheels ie. the conveyor moves inthe same direction as the jet. If so, then the discussions around what happens if the conveyor is moving in the opposite direction to the jet are not the same scenario, though because they are interesting and probably the source of much of the confusion I think they are worth discussing. The wording of the question when considering jet and conveyor moving in opposite directions creates the possibility for a breakdown in logic. This is not me saying something can't happen, but me pointing out the breakdown in the logic. We know the plane can move along the conveyor - it has jet engines producing enormous thrust which is only opposed by trivial friction at the wheels/wheel bearings plus trivial air resistance. If the plane moves along the conveyor its wheelspeed cannot be exactly matched by the conveyor (i won't repeat the reasoning). If the problem is presented with the intention that conveyor and jet are travelling in opposite directions (which I don't think it is) then the logic breaks down if wheelspeed is coupled to conveyor speed - the jet cannot travel along the conveyor and at the same time have the same wheelspeed as the conveyor. This doesn't mean the conveyor is somehow preventing takeoff it is simply a problem with how the question is worded.

If I'm not being clear then apologies (and I'm thinking I probably won't include this puzzle in our next pub quiz!)

 

[Deleted member 36735]

Nothing could be further from the truth, when you're pressed to give answers based on science fact you're unable to and simply ignore them and quote but it's the rules.

That's a shockingly inaccurate analysis of the conversation.
The rules of the puzzle have to be observed, anything else is irrelevant.
What answers on "science fact" have I been asked to give?

other than that your constant fall back is the exact type of reply your just given.
I suppose it beats your plane that stops dead if we roll this in reverse

I'm big enough to say that the "plane stopping dead" was probably worded badly, not explained properly and sounds silly. It's called a mistake, I made it and own it.

But as usual all you have done is criticise and offered absolutely nothing.

Have you actually sat on a big plane and taken off?

 

[Deleted member 36735]

The scenario in the OP I believe is that the conveyor moves to counteract the rotation of the wheels ie. the conveyor moves in the same direction as the jet.

That is a logical understanding of the "counteracting" that is acknowledged.

If so, then the discussions around what happens if the conveyor is moving in the opposite direction to the jet are not the same scenario, though because they are interesting and probably the source of much of the confusion I think they are worth discussing.

However, "counteracting" can also mean that the conveyor is moving backwards in relation to the plane, so that's a legitimate thought process that many of us have held too! Hey, maybe we're wrong, no problem with that but it's a valid interpretation.

Most of us in the discussion can see both points of view, unfortunately as always a small number of pigeons can't and resort to their "because I'm right" mentality.

 

[Deleted member 35927]

That's a shockingly inaccurate analysis of the conversation.
The rules of the puzzle have to be observed, anything else is irrelevant.
What answers on "science fact" have I been asked to give?

I'm big enough to say that the "plane stopping dead" was probably worded badly, not explained properly and sounds silly. It's called a mistake, I made it and own it.

But as usual all you have done is criticise and offered absolutely nothing.

Have you actually sat on a big plane and taken off?

There you go again, same old reply. I've asked multiple times how you account for the thrust generated by the engines. The wheels offer no resistance and you can't just wish it away by magic. So how do you stop the plane moving forward.
You need an opposing force, that isn't magical

 

[SwingsitlikeHogan]

I suppose it is true that it is irrelevant to answering the puzzle as posed whether or not there would be sufficient thrust to overcome friction and hence to enable the aircraft to take off.

The puzzle as posed declares that the aircraft thrust is not sufficient to provide any forward motion of the aircraft relative to the ground. Unrealistic yes - and I could argue how unrealistic it is until I am blue in the face - but that does not change the premis of the puzzle. So simply taken as stated..i.e. no forward motion relative to the earth axes set (just thought I'd chuck that in as I used to design missile and aircraft navigation systems) due to thrust not sufficient to overcome the effect on the aircraft of the belt - then the wings will not provide any lift and the aircraft will not take off.

 

[Voyager EMH]

(just to clarify, this is not relevant to the OP problem). The displacement is the difference here. After pushing your dinky toy along the travolator it has moved a certain distance in a certain time ie. it has gained velocity. In order for this displacement to occur, the wheels must have moved faster than the travolator belt (or else your dinky toy would still be in the same spot (relative to an outside observer).

On a travellator with constant speed, yes, the wheels increase rotation speed when holding still is changed to pushing forward.

But to go back to the OP scenario, if the travellator increases in speed to match the increase in speed of rotation of the dinky toy's wheels that the push induces, then the push still results in the dinky toy moving forwards.

Oh no, I've gone past my 9pm rule for posting after wine has been drunk. I'm sure to have done something I'll regret later.

 

[Bobski]

On a travellator with constant speed, yes, the wheels increase rotation speed when holding still is changed to pushing forward.

But to go back to the OP scenario, if the travellator increases in speed to match the increase in speed of rotation of the dinky toy's wheels that the push induces, then the push still results in the dinky toy moving forwards.

Oh no, I've gone past my 9pm rule for posting after wine has been drunk. I'm sure to have done something I'll regret later.

That's the problem - if the travolator increases its speed (and assuming no skidding etc) then that increase is also transmitted to the wheels. The wheels will always be going faster (as long as the toy is being pushed) and the travolator will be forever increasing its speed trying to catch up. If however, the travolator was programmed to match the speed of the toy (rather than its wheels) it could do so without an issue.

Wine sounds like a great idea - and time to catch the end of the footie

 

[Deleted member 36735]

There you go again, same old reply. I've asked multiple times how you account for the thrust generated by the engines. The wheels offer no resistance and you can't just wish it away by magic. So how do you stop the plane moving forward.
You need an opposing force, that isn't magical

As has been stated many many many times, the opposing force is the conveyor belt moving in the opposite direction to the plane. To make it easy, once the plane gets up to 5mph on the "ground", ie the conveyor belt, the belt according to the rules is also travelling at 5mph backwards in relation to the plane so the plane doesn't move forward at all.

Each time the plane increases by 1mph, so does the conveyor. It is irrelevant what is powering the wheels, they don't jump or skid forward, they rotate but so does the conveyor in the opposite direction.

HOWEVER, IT IS ALSO POSSIBLE TO AGREE WITH YOU THAT THE CONVEYOR IS MOVING FORWARD.
There can be 2 interpretations of the "counteracting" sentence.

 

[Deleted member 36735]

I suppose it is true that it is irrelevant to answering the puzzle as posed whether or not there would be sufficient thrust to overcome friction and hence to enable the aircraft to take off.

The puzzle as posed declares that the aircraft thrust is not sufficient to provide any forward motion of the aircraft relative to the ground. Unrealistic yes - and I could argue how unrealistic it is until I am blue in the face - but that does not change the premis of the puzzle. So simply taken as stated..i.e. no forward motion relative to the earth axes set (just thought I'd chuck that in as I used to design missile and aircraft navigation systems) due to thrust not sufficient to overcome the effect on the aircraft of the belt - then the wings will not provide any lift and the aircraft will not take off.

HALLELUJAH.

I think that's the issue some are having, they are confusing what normally happens versus just sticking to the actual written word.

 

[Deleted member 35927]

As has been stated many many many times, the opposing force is the conveyor belt moving in the opposite direction to the plane. To make it easy, once the plane gets up to 5mph on the "ground", ie the conveyor belt, the belt according to the rules is also travelling at 5mph backwards in relation to the plane so the plane doesn't move forward at all.

Each time the plane increases by 1mph, so does the conveyor. It is irrelevant what is powering the wheels, they don't jump or skid forward, they rotate but so does the conveyor in the opposite direction.

HOWEVER, IT IS ALSO POSSIBLE TO AGREE WITH YOU THAT THE CONVEYOR IS MOVING FORWARD.
There can be 2 interpretations of the "counteracting" sentence.

How does a conveyor who's only contact with the plane is via freely rotating wheels that offer next to no resistance counter 250000 lbs of thrust produced by an object that is pushing against the air?

 

[Deleted member 35927]

HALLELUJAH.

I think that's the issue some are having, they are confusing what normally happens versus just sticking to the actual written word.

The exact written word, as per your posted definition of counteracts has the belt moving in the same direction as the plane.

 

[Swango1980]

The OP doesn't declare what the wheels actually do in reality. The OP says it has been "programmed". So, even if there is a debate as to what the programmer is trying to achieve, there are 2 options:

Option 1: Belt in opposite direction to plane. In this scenario the programmer could set the program to match the wheel speed, in opposite direction to plane movements. Of course, this would be impossible to actually achieve, belt could never catch up with wheel speed and so would exponentially increase.

Option 2: Belt in same direction as plane. This is possible, and the belt would counter the rotation of the wheels.

Regardless, in both Options, the plane takes off normally. The only difference is how fast the wheels rotate, which are free wheeling. The question was, does the plane take off. So, the "puzzle" can be answered. Yes, the plane does take off.

The only way the answer in No, is if there is no effort to engage the engines to actually attempt a take off, or if the belt is like the picture, and plane crashes off the front.

But, making up the Laws of Nature to justify the plane not taking off is a cop out. No point in a "puzzle" if you can just invent your own science to fit.

 

[RichA]

That's the problem - if the travolator increases its speed (and assuming no skidding etc) then that increase is also transmitted to the wheels. The wheels will always be going faster (as long as the toy is being pushed) and the travolator will be forever increasing its speed trying to catch up. If however, the travolator was programmed to match the speed of the toy (rather than its wheels) it could do so without an issue.

Wine sounds like a great idea - and time to catch the end of the footie

Yep. That's the point I keep repeating. The 300 ton plane has to basically skid /wheelspin it's way to takeoff speed of 180mph relative to the surface of the conveyor belt. Friction, heat, mechanical failure.

 

[Deleted member 36735]

How does a conveyor who's only contact with the plane is via freely rotating wheels that offer next to no resistance counter 250000 lbs of thrust produced by an object that is pushing against the air?

You obviously don't understand how the plane normally moves forward on a runway from a standing start, this is part of the problem with your comprehension.

The plane doesn't fly through the air from a standstill, the engines push it forward and the tyres react with the opposite force of the solid tarmac to allow the plane to roll.

If there is no solid resistance, the plane can't roll. And guess what, the conveyor moving in the opposite direction as per one interpretation of the scenario is the lack of solid resistance.

 

[Deleted member 36735]

The exact written word, as per your posted definition of counteracts has the belt moving in the same direction as the plane.

Well, recurring theme going on here, your lack of comprehension.

The "counteracting" has different meanings which could mean that the belt is either moving in the same direction as the plane or in the opposite direction. Both are valid, that's the point of the original puzzle.

Clearly you haven't read all the posts to see that this has already been acknowledged as a recognised point of different interpretation.