Plane

[Deleted member 35927]

How about a slightly different experiment..

Same conveyor
This time I'm stood next to it holding a skateboard in place on the conveyor
As I walk forward the conveyor and push the board it matches the speed of the wheels , perfectly counteracting their rotation.
If what esat and co are saying is true , I would not be able to move as skateboard is held in some strange state.
We no that this is nonsense and even if you send the conveyor to 1000mph it won't make any difference to me or the board. With minimal effort I can keep walking along side and keep pushing the board.
As with the plane the interaction is with the wheels and neither me or the plane know any different

Now put wings on the board and attachs jets and tell me how that won't move forward in the same way ?

N.b i said a walking but could just as easy be flying alongside wearing a jetpack

 

[Deleted member 35927]

So now you're saying that the conveyor belt / treadmill goes forwards?
You are always very certain that you are correct, even when contradicting yourself.

You worked out the correct answer but then doubled down on the wrong answer the very next day .

 

[RichA]

You worked out the correct answer but then doubled down on the wrong answer the very next day .

Changed my mind - yep.
Owned it - yep.
Denied or concealed changing my mind - nope.

 

[RichA]

How about a slightly different experiment..

Same conveyor
This time I'm stood next to it holding a skateboard in place on the conveyor
As I walk forward the conveyor and push the board it matches the speed of the wheels , perfectly counteracting their rotation.
If what esat and co are saying is true , I would not be able to move as skateboard is held in some strange state.
We no that this is nonsense and even if you send the conveyor to 1000mph it won't make any difference to me or the board. With minimal effort I can keep walking along side and keep pushing the board.
As with the plane the interaction is with the wheels and neither me or the plane know any different

Now put wings on the board and attachs jets and tell me how that won't move forward in the same way ?

If the wheels and conveyor are perfectly speed matched, their touching surfaces will travel exactly the same distance in any given period of time.
The wheels on the skateboard will travel the additional distance that you walk. Therefore they were faster and not perfectly speed matched.
Method of propulsion is irrelevant.

 

[SocketRocket]

How about a slightly different experiment..

Same conveyor
This time I'm stood next to it holding a skateboard in place on the conveyor
As I walk forward the conveyor and push the board it matches the speed of the wheels , perfectly counteracting their rotation.
If what esat and co are saying is true , I would not be able to move as skateboard is held in some strange state.
We no that this is nonsense and even if you send the conveyor to 1000mph it won't make any difference to me or the board. With minimal effort I can keep walking along side and keep pushing the board.
As with the plane the interaction is with the wheels and neither me or the plane know any different

Now put wings on the board and attachs jets and tell me how that won't move forward in the same way ?

N.b i said a walking but could just as easy be flying alongside wearing a jetpack

If you stood on a trailer that was being towed at a constant speed, then you ran along the trailer in the opposite direction to what it was moving at the same speed as the trailer moved, then jumped off when you reached the end. What would happen when you landed on the road?

 

[Deleted member 35927]

If the wheels and conveyor are perfectly speed matched, their touching surfaces will travel exactly the same distance in any given period of time.
The wheels on the skateboard will travel the additional distance that you walk. Therefore they were faster and not perfectly speed matched.
Method of propulsion is irrelevant.

Thats the point, the conveyor cannot stop me or skateboard accelerating away no matter what it does, it's acting only on the passive wheels of the board.

 

[Deleted member 35927]

If you stood on a trailer that was being towed at a constant speed, then you ran along the trailer in the opposite direction to what it was moving at the same speed as the trailer moved, then jumped off when you reached the end. What would happen when you landed on the road?

break an arm, maybe a leg too?

 

[Swango1980]

So now you're saying that the conveyor belt / treadmill goes forwards?
You are always very certain that you are correct, even when contradicting yourself.

Nope. If you read back I explained Crow's explanation to Eesat (think I even used a bullet point list). I have even discussed it with you.

However, there are also many that are clearly wedded to this being a traditional treadmill, operating in reverse to direction plane wants to travel. I have continually explained how that is impossible as soon as the engines are used to produce thrust

 

[Bobski]

Had hoped my first post onthe forum would be about golf, but ......
I was thinking of using the jet on a treadmill in our local pub-quiz and drew up a graphic to deal with the likely controversy/fall-out. I've modifird it a bit in the hope it might be of usefulness in this thread. I think the wording to the problem is key, with a few different versions across the internet - it works better IMHO if presented so that the treadmill matches the jet's speed (rather than the jet's wheel-speed) for the reasons outlined in the graphic. In this scenario the jet takes off in normal fashion, the problem only catching out those who forget the jet's wheels are not driven. In the scenario where the treadmill speed must match wheel speed (travelling in the opposite direction), the physics for the plane is still that it should accelerate and take off, but the problem is that the treadmill is forced into an acceleration loop which for all practical purposes is impossible. Folk who see this will argue (correctly) that the jet cannot travel along the treadmill without defying the pre-requisite, whilst others argue (correctly) that what is happening at the wheels can not restrain the thrust generated by the jet engines. Interestingly, this isn't the case if the treadmill moves in the same direction as the plane (as I think the wording on this forum's OP suggests).

Apologies if this post isn't helpful (and I'll stick to golf in future!)

Cheers!

 

[Swango1980]

Given that we are all happy that we know how wings work, and all the focus is on the wheels and conveyer belt, just wanted to confirm:

Are there are genuinely people that believe the forward movement of a Jumbo using 100,000 pounds of thrust can be stopped by the force of a treadmill operating in the opposite direction?

Meanwhile, if a trolly was on the same treadmill operating the same speed, I could physically hold it from moving back with the treadmill, despite that treadmill exerting the same huge "force" it applied to the Jumbo?

I'm sure people can't possibly think that, so I just wanted to double check

 

[RichA]

Thats the point, the conveyor cannot stop me or skateboard accelerating away no matter what it does, it's acting only on the passive wheels of the board.

From the puzzle you posted to initiate this conversation... "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation."

But you're saying that it's easy - you just ignore that one very specific rule and get your wheels going faster than the belt.

Essentially saying that it's a paradox so you have to cheat to solve the puzzle is not the same as understanding and solving it, as you had claimed.

 

[Deleted member 35927]

From the puzzle you posted to initiate this conversation... "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation."

But you're saying that it's easy - you just ignore that one very specific rule and get your wheels going faster than the belt.

Essentially saying that it's a paradox so you have to cheat to solve the puzzle is not the same as understanding and solving it, as you had claimed.

No you can have the belt going whatever speed you want, makes no difference, the fact you worked this out but then flipped is quite surprising

 

[RichA]

No you can have the belt going whatever speed you want, makes no difference, the fact you worked this out but then flipped is quite surprising

You're making no sense.
Do you agree that for your plane, skateboard, shopping trolley or whatever to move forwards, it must break the rule about "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation"?

 

[SocketRocket]

break an arm, maybe a leg too?

Why?

 

[Deleted member 35927]

You're making no sense.
Do you agree that for your plane, skateboard, shopping trolley or whatever to move forwards, it must break the rule about "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation"?

The conveyor simply speeds up to match the wheel speed that's as its been programmed to do. Don't forget the wheels have no drive so must be moving ahead with the belt always playing catch-up.

It simply cannot stop me , and the effort for me to move it does not change regardless of the belt speed.

 

[Deleted member 35927]

Why?

The ground is hard and I landed funny.

 

[backwoodsman]

From the puzzle you posted to initiate this conversation... "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation."

But you're saying that it's easy - you just ignore that one very specific rule and get your wheels going faster than the belt.

Essentially saying that it's a paradox so you have to cheat to solve the puzzle is not the same as understanding and solving it, as you had claimed.

After more thought, I've also come to this conclusion - ie its a paradox.

In what one might imagine as 'real life', the plane will take off. The thrust (force) generated by the engines is such that the plane will move forward, and eventually take off. But for the plane to move forward in relation to the ground, its wheels must be going a bit faster than the conveyor belt (or skidding) - otherwise the plane would be standing still in relation to the ground. But the OP states that the speed of the wheels and the conveyor belt are perfectly in 'sync' - which means the plane can't be moving forward and must standing still in relation to the ground. Both can't be true at the same time.

So, yes, the plane will take off but the wheels can't be in sync with the conveyor. But the problem states they are in sync. So round we go with the argument.

 

[Deleted member 35927]

After more thought, I've also come to this conclusion - ie its a paradox.

In what one might imagine as 'real life', the plane will take off. The thrust (force) generated by the engines is such that the plane will move forward, and eventually take off. But for the plane to move forward in relation to the ground, its wheels must be going a bit faster than the conveyor belt (or skidding) - otherwise the plane would be standing still in relation to the ground. But the OP states that the speed of the wheels and the conveyor belt are perfectly in 'sync' - which means the plane can't be moving forward and must standing still in relation to the ground. Both can't be true at the same time.

So, yes, the plane will take off but the wheels can't be in sync with the conveyor. But the problem states they are in sync. So round we go with the argument.

No it's not a paradox, it's easily explained with basic science and has been multiple times.
Time for bed I think and see what other bonkers stuff appears by the morning.

 

[backwoodsman]

Paradox may, or may not, be the correct word.

Yes the plane will take off. The thrust generated means that will happen. But in doing so, the wheels cannot be in perfect sync with the conveyor. But if the wheels are in perfect sync with the conveyor, it cant move forward. So the conditions of the problem can't be met.

 

[RichA]

The conveyor simply speeds up to match the wheel speed that's as its been programmed to do. Don't forget the wheels have no drive so must be moving ahead with the belt always playing catch-up.

It simply cannot stop me , and the effort for me to move it does not change regardless of the belt speed.

Well this is new and contradicts "The conveyor belt is programmed to match the speed of the plane's wheels in the opposite direction, perfectly counteracting their rotation."

I don't get why you keep banging on about drive.
If I'm driving my car in 5th gear at 70mph, my speed is 70mph.
If my car is in neutral going down a hill at 70mph, my speed is 70mph.
If I'm on roller skates with a jet pack on my back doing 70mph, my speed is 70mph.
If I'm in a jumbo jet on a conveyor belt that perfectly opposes the speed of my wheels, which are rotating at 70mph, I'm stationary. If my jumbo jet starts moving down the conveyor belt at 70mph then it's wheels are rotating 70mph faster than the conveyor belt is moving and I'm not complying with the fundamental rule of the puzzle.