Skill's weekend teaser

[TheBramble]

I think we should let Skills decide.

 

[Atilla]

Indirectly, this has been one of the most informative thread regarding trading and behaviour for ages.

I couldn't give a toss if the plane takes off, but do wonder why they'd put it on a conveyor belt in the first place?

It was a simulation exercise to teach bird brains not to fly into aeroplanes...

I read about it in the Metro... :cheesy:

 

[Hotch]

Once again (keep being sucked in)...relativity. As said numerous times, and what keeps being ignored, the conveyor belt moves the speed of the plane, not the wheels.

Bramble didn't understand the relativity involved and that's why he has a paddy about my previous post explaining that the speed of the plane isn't the speed of the wheels. Let's take a treadmill example, if I'm running on a treadmill at 10mph, and the treadmill is moving backwards at 10mph, how fast am I going? Well it's relative isn't it. If you're off the treadmill, I'm moving at 0mph, if you're on the treadmill, I'm moving at 4mph. Hopefully this explains why the plane moves, and yet the treadmill moves at the speed of the plane.


Ala "Bramble maths" :

The wheels on the plane move at 2x, the speed of the plane is x, the speed of the conveyor belt is -x

speed of wheels - speed of belt = speed of plane.

2x-x=x

Wahey, plane moves

"I just did the maths"


Apologies if this post seems a bit stressy, I've been trying to keep my cool, but science is being ruined!

xkcd - A Webcomic - Science

P.S. xkcd • View topic - Airplane On A Treadmill

 

[Atilla]

You must be a creative accountant... Hotch??? :cheesy:

Here is the original question for reference.

Imagine a 747 sitting on a very large conveyor belt. The belt has the same dimensions as a runway at an airport*, and is set up to exactly match the speed of the plane's wheels, moving in the opposite direction. What will happen?

Same rules as before please; no explanation for a little while, no Googling, everyonerich you are banned from participating**.

SL

*To save confusion, the conveyor belt is the same length as the distance required for a 747 to take off from a normal runway; the frictional co-efficient of runway tarmac and the belt are identical, all other variables such as wind and atmospheric conditions can be ignored.
**I'm just kidding (but not really).

What you have explained and what's in the question are about 360 degrees apart... :cheesy:

 

[TheBramble]

Let's take a treadmill example, if I'm running on a treadmill at 10mph, and the treadmill is moving backwards at 10mph, how fast am I going? Well it's relative isn't it. If you're off the treadmill, I'm moving at 0mph

Exactly. You’ve just spelt out precisely my proof. So what is it about this you’re not getting?

The wheels on the plane move at 2x, the speed of the plane is x, the speed of the conveyor belt is -x
2x-x=x

How can the wheels on the plane move at twice the speed of the plane? We’re back to peto and his magic wheels again.

If the plane moves at 2X the belt moves backward at 2X.
If the plane moves at X the belt moves backward at X.
If the plane moves at 0 the belt moves backward at 0.
If the plane moves at 1,000,000 mph the belt moves backward at 1,000,000 mph.
Net result is ALWAYS ZERO motion relative to fixed reference point (as you’ve confirmed above Hotch)

speed of wheels - speed of belt = speed of plane.

Correct. And we are told by Skills that the speed of wheels and speed of conveyor are set to match exactly.

 

[Atilla]

Let's take a treadmill example, if I'm running on a treadmill at 10mph, and the treadmill is moving backwards at 10mph, how fast am I going? Well it's relative isn't it. If you're off the treadmill, I'm moving at 0mph, if you're on the treadmill, I'm moving at 4mph. Hopefully this explains why the plane moves, and yet the treadmill moves at the speed of the plane.

NOPE!


If I'm off the treadmill then you are on the treadmill moving backwards at 10mph from me whilst running towards me at 10mph.



Don't get me started on the 4mph...

 

[megamuel]

So when the plane fires up its engines and flies off.... I mean, remains static on the runway... Where is the resistance coming from? What is stopping the plane moving forwards?

 

[Hotch]

NOPE!


If I'm off the treadmill then you are on the treadmill moving backwards at 10mph from me whilst running towards me at 10mph.



Don't get me started on the 4mph...

4mph was a typo obv, meant to be 10. Dunno what your post is trying to say.

Once more...

The treadmill is supposed to move at the speed of the plane, viewed from someone standing off the treadmill, hence the plane has to be moving forward, relative to said person, for the treadmill to move (aka, moving through the air). The speed of the plane relative to said person, is half the speed the wheels are spinning.

 

[Atilla]

4mph was a typo obv, meant to be 10. Dunno what your post is trying to say.

Once more...

The treadmill is supposed to move at the speed of the plane, viewed from someone standing off the treadmill, hence the plane has to be moving forward, relative to said person, for the treadmill to move (aka, moving through the air). The speed of the plane relative to said person, is half the speed the wheels are spinning.

Lets clarify.

Conveyor or treadmill is spinning or moving?

If belt is spinning but not moving then plane is static. ie Like man running on a treadmill.

If moving physically whilst belt is spinning then plane moving with the conveyor belt. ie Like man on a bus.

The length of conveyor belt is irrelevant unless someone has locked the belt from moving.

If friction coefficient of runway and belt are the same --- what does this mean. Conveyor belt it is all but in name - still a runway called a conveyor belt?

My dog is called Atilla but at the end of the day he will die a dog. Atilla is already dead but is not and was not a dog.

I think I'm becoming saturated with this thread. :cheesy:

 

[new_trader]

Indirectly, this has been one of the most informative thread regarding trading and behaviour for ages.

I agree 100%. There are those interminably focusing on irrelevant details whilst others understood the intent of the questioner.

I seriously hope only 10% say the plane will take off.

 

[Hotch]

Lets clarify.

Conveyor or treadmill is spinning or moving?

If belt is spinning but not moving then plane is static. ie Like man running on a treadmill.

If moving physically whilst belt is spinning then plane moving with the conveyor belt. ie Like man on a bus.

If friction coefficient of runway and belt are the same --- what does this mean. Conveyor belt it is all but in name - still a runway called a conveyor belt?

NOTA, the belt is spinning and the plane moves. The conveyor belt is the same as the runway, except it's moving out from under the plane.

I have run out of ways of explaining this, I'm sure if someone read my posts before deciding I'm wrong they'd understand. There's even video evidence somewhere in here.
...
...
...
...

The plane is on a treadmill which is not moving, plane turns engines on, moves forward at 1mph, the treadmill "spins" at 1mph in the opposite direction, all this does is spin the wheels around 1mph faster. Hence the plane continues to move forward.

 

[Atilla]

NOTA, the belt is spinning and the plane moves. The conveyor belt is the same as the runway, except it's moving out from under the plane.

I have run out of ways of explaining this, I'm sure if someone read my posts before deciding I'm wrong they'd understand. There's even video evidence somewhere in here.
...
...
...
...

The plane is on a treadmill which is not moving, plane turns engines on, moves forward at 1mph, the treadmill "spins" at 1mph in the opposite direction, all this does is spin the wheels around 1mph faster. Hence the plane continues to move forward.

No comprehendo!

1. Are we talking man in a bus (with moving bus) or
2. Man running on a treadmill (with stationary treadmill)?

1 or 2?

If you want to complicate things feel free to change man to aeroplane and bus to conveyor.

x=b
y=c

x+y=b+c


1 or 2?

 

[raysor]

should be man walking. If running both feet are off the ground at some moment. That would be like the plane bouncing along the runway/belt.

 

[megamuel]

No comprehendo!

1. Are we talking man in a bus (with moving bus) or
2. Man running on a treadmill (with stationary treadmill)?

1 or 2?

If you want to complicate things feel free to change man to aeroplane and bus to conveyor.

x=b
y=c

x+y=b+c


1 or 2?

I think he's talking about a plane on a conveyor belt! The engines push the plane forward, the wheels move, the runway moves, the plane moves faster, the wheels move faster, the runway moves faster, the all accelerate, until, the plane takes off. Thats it.

 

[TheBramble]

I think he's talking about a plane on a conveyor belt! The engines push the plane forward, the wheels move, the runway moves, the plane moves faster, the wheels move faster, the runway moves faster, the all accelerate, until, the plane takes off. Thats it.

Stunning.

Can you give us a roughly worked example of at what point the plane moves faster forward than the conveyor belt moves backward? Ta.

 

[megamuel]

I'm too busy to spend 20 pages explaining it to you. I was just explaining it for the other guy. By the way, I didn't say the plane moves faster than the runway. The runway matches the speed of the plane. So when the plane goes faster (because its engines are pushing it), the runway goes faster in the opposite direction. All that means is that the wheels are spinning twice as fast than they would normally when the plane takes off.

 

[Atilla]

I'm too busy to spend 20 pages explaining it to you. I was just explaining it for the other guy. By the way, I didn't say the plane moves faster than the runway. The runway matches the speed of the plane. So when the plane goes faster (because its engines are pushing it), the runway goes faster in the opposite direction. All that means is that the wheels are spinning twice as fast than they would normally when the plane takes off.

1. Are we talking aeroplane on a conveyor belt (with conveyor moving horizontally) or
2. Aeroplane on a conveyor belt (with rotating conveyor belt that is stationary on the ground)?

1. Are we talking man in a bus (with moving bus) or
2. Man running on a treadmill (with stationary treadmill)?



1 or 2? :clap:

2 or 1? :clap:

 

[megamuel]

Atilla,

Its like this YouTube - Mythbusters - Plane on a Conveyor Belt
Big long piece of material instead of a treadmill, but same principal. This plane normally takes off at around 60-70mph, as you will see, the truck is pulling its runway in the opposite direction at 60-70mph, but the plane still accelerates and takes off.

Sam.

 

[raysor]

Atilla,

Its like this YouTube - Mythbusters - Plane on a Conveyor Belt
Big long piece of material instead of a treadmill, but same principal. This plane normally takes off at around 60-70mph, as you will see, the truck is pulling its runway in the opposite direction at 60-70mph, but the plane still accelerates and takes off.

Sam.

Oh yes I can see the wheels turning in sync with the material!!

 

[Atilla]

Atilla,

Its like this YouTube - Mythbusters - Plane on a Conveyor Belt
Big long piece of material instead of a treadmill, but same principal. This plane normally takes off at around 60-70mph, as you will see, the truck is pulling its runway in the opposite direction at 60-70mph, but the plane still accelerates and takes off.

Sam.

Not a scientific test is it!


Planes wheels are touching the ground. Propellor turning and still travelling with respect to the ground.


That's hardly a conveyor belt either? More like someone pulling the rug from under the tyres.


Be good if you people could use the Queens English to communicate more effectively. :cheesy: