A puzzle for all.

[arranj]

In order for the plane to move even 1 metre - the wheels would have to have "gone quicker" than the conveyor - hence a question rule break.
I understand the wheels aren't driven, but assuming no tyre slip they are being dragged by the thrusters.
The question fails as soon as there is the first movement forwards by the plane, which there inevitably is.

[stunned_monkey]

bozzzydmc Wrote:If the wheels and conveyor are moving at the same speed

Let's deal with that first. Whatever happens, the wheels will of course ROTATE at the speed of the conveyor.

Quote:surely the plane doesnt move forward, the plane is stationary....

Why? How can the conveyor stop it moving? The plane is on wheels that are free spinning. They'll just spin faster. The conveyor can't apply a force on the plane.

[arranj]

Imagine no conveyor, but 2 powered rotating drums, the same diameter as the planes wheels.

Paint a straight white line across the side of the tyres and the drums (to mark the relative positions).

Start the conveyor slowly. (the plane stays still)
After one rotation the markings still line up.
Good - they are both going the same speed.

Now start the engines.

Disaster - the plane has fallen off the drums.

and as a bi-product the wheels have (relative to the plane) gone faster than the drums. Hence a rule break. It can't be done and comply with the rules

[bozzzydmc]

Yes i get your point but....

in this case its the engines making the wheels rotate forward from zero mph... they dont 'kick in' once the wheels are rotating. :? :?

[arranj]

Umm - well anyway - the plane takes off. Of that I'm certain now.

Since the plane is not attached to the conveyor belt - the engines propell the plane forward at it's normal speed (minus bearing friction) and it takes off in it's normal time.
At the time of take off the wheels are rotating at "take off speed plus infinity", since the conveyor belt is forever catching up with the wheels that are inevitably being dragged faster than it. This is assuming (as before) infitessimal lag and 100 percent tyre/conveyor friction.

In this case the plane takes off and the "impossible" question condition "conveyor=wheel speed" is almost obeyed (infitessimally), but not quite, due to inertia - i.e. plane moves first.

[Outatime]

Glad this topic ends in a rather peaceful way.... unlike what I saw on other forums after a search on goggle which ends with forced termination by the moderator. :lol:

Gosh, it's time to change my mind back to DeLorean topics I recently day dream with a plane on running machines!

[bozzzydmc]

Tee hee :o

Well it was a good topic to discuss, im sure it wont be the last on it .......

[Rich H]

RichH Wrote:Absolutely not.

Where's the lift coming from?

And after spending an hour at the unit soldering audio cables, I've changed my mind.

Wow, three pages worth of posts since then :lol:

Of course it'll take off.....doh!!

[Guinney1971]

a group of us were discussing this in the pub last night, and everyone eventually agreed that yes the plane will take off.

Mind you, then the conversation digressed onto the Universe, 'Big Bang Theory', where did all the 'matter' come from that caused the big bang come from in the first place, what is the universe actually expanding into..... Quite an intelligent conversation really for a Saturday night in the Nags!! :lol:

[NickT]

The plane moves forward because of newtons third law of motion of the engine thrust against the mass of the plane.

THE WHEELS ARE NOT DRIVEN THEY ARE FREE WHEELING !

If it was a car and a conveyor then the car would not move.

Draw a force diagram!

John's analogy with the person an FREEWHEELING roller skates is a good analogy.

NickT

ps Claire, please enlighten us with the other big question......

WOMEN

[Guinney1971]

WOMEN????

Dont ask me mate!!! I've got more friends who are blokes then women cos I dont understand 'em either! lol :lol:

I could never stand working in an office full of women, cos they were always bitching about someone or something or flapping their gums about some shite on TV.......used to do my head in :roll:

Maybe thats why I've stayed around a male dominated environment like the motor trade for so long - WYSIWYG :lol:

[NickT]

WYSIWSG, if only more people were like this !

Here is another puzzling question,

.....when will I finish my Delorean restoration?

NickT.

[Outatime]

Nick, any perfectionist kinda guy will never find an end to their DeLorean Project....

It's a never ending story!

[bozzzydmc]

NickT Wrote:Here is another puzzling question,

.....when will I finish my Delorean restoration?

NickT.

Gee the questions just keep on getting harder and harder.....