Who's right?

[blighter]

speaking of flying red bull gives you wings

it also stops you been able to go to sleep even at 3 am :/

its Red Rooster, its different it's £1.60 for 2 x 1l bottles at farmfoods red bull is like £1.60 for a can

back on topic before yewen deletes all my posts...
the plane will take off if it has enough runway (or if its small enough )

EDIT: i'm a 16 yr old college student... of course i'm a cheapskate
EDITEDIT: VIRII, have added you to my live friends list (i'm "Chez the Second")

 

[VIRII]

its Red Rooster, its different it's £1.60 for 2 x 1l bottles at farmfoods red bull is like £1.60 for a can

Cheapskate huh

 

[tim_enchanter]

What is needed is a good explanation as to why the wheels and treadmill have no or little effect on moving the plane forward or stopping it moving forward.

Yep, going back to scams shopping trolley.

If you hold the shopping trolley on the conveyor and stand on solid ground next to it, you can run forwrd moving the trolley forward.
While doing that the conveyor and trolley wheels can go at any speed or direction they like, there is no way it can stop you pushing the trolley forward.
The same goes with the planes engines pushing against the air

And to use your example of a trolley. Imagine you are in an airport and have a trolley. You come to the moving walkway and decide to walk on the normal surface but reach across and push your trolley along the moving walkway. If you are walking against the flow of the moving walkway, you can still push the trolley forward, regardless of what speed you or the walkway are moving at because the force you are applying is against a plane other than the walkway.

The trolley is an aeroplane.
The moving walkway is the conveyor runway.
You are the aircraft engines.

That covers it in my opinion

 

[Macro]

And to use your example of a trolley. Imagine you are in an airport and have a trolley. You come to the moving walkway and decide to walk on the normal surface but reach across and push your trolley along the moving walkway. If you are walking against the flow of the moving walkway, you can still push the trolley forward, regardless of what speed you or the walkway are moving at because the force you are applying is against a plane other than the walkway.

The trolley is an aeroplane.
The moving walkway is the conveyor runway.
You are the aircraft engines.

I see what you mean...

Hang on, brain melting...

OK, gotten to the bottom of it....

Nicked from elsewhere on t'internet

The issue is that the question has been specifically worded to cause to differing opinions in two types of people.

The practical thinkers will assume that the plane is using it’s engines and that the thrust will simply push it forwards, regardless of the conveyor’s speed, as the frictional force between the conveyor and the wheels is negligible and the thrust from the engines acts upon the air and not the wheels. They will say the the plane does take off, and they’d be correct.

However, the theoretical thinkers will ignore the real-world practicalities of the situation because it would never exist. Instead they abstract it to a simple object with a given speed, which is being kept motionless by something exerting a force in the opposite direction. They correctly calculate that the net speed of the object will be nothing and therefore there would be no airflow over the wings of the plane to allow it to take off.

i.e. If the plane applies no power and the belt moves -10 ft in one second, then the plane moves 0 + (-10) = -10 ft. However, if the plane applies power to move over the belt at +10 ft in one second, then you have +10 + (-10) = 0.

This assumes you are matching wheelspeed to belt speed which is one of two possible interpretations, the other that you match belt speed to ground speed which results in wheelspeed double the groundspeed.

In reality, both answers are equally valid depending on your point of view and how you interpret the question, which has been worded very badly (on purpose, I’m sure).

Which explains why having now done a quick search this is a conudrum which is all over t'internet and not a straight forward question and answer.

 

[JRS]

I can't adequately verbalise why the wheels (which are not direct driven) on the plane have little effect on a treadmill but the forces involved are very different in size and direction. I guess there comes a point where the downwards force (mavity) keeping the wheels in contact with the treadmill is simply insignificant compared to the forward thrust so the wheels will simply skid forward / lose grip on the treadmill even if still turning.

They won't skid or lose grip - the wheels are free to rotate as fast as they like. The friction force (co-efficient of friction between wheels and treadmill multiplied by the reaction force, i.e. weight of the aircraft) would only come into play if the wheels were being driven or braked, and they aren't.

 

[blighter]

I see what you mean...

Hang on, brain melting...

OK, gotten to the bottom of it....

Nicked from elsewhere on t'internet

The issue is that the question has been specifically worded to cause to differing opinions in two types of people.

The practical thinkers will assume that the plane is using it’s engines and that the thrust will simply push it forwards, regardless of the conveyor’s speed, as the frictional force between the conveyor and the wheels is negligible and the thrust from the engines acts upon the air and not the wheels. They will say the the plane does take off, and they’d be correct.

However, the theoretical thinkers will ignore the real-world practicalities of the situation because it would never exist. Instead they abstract it to a simple object with a given speed, which is being kept motionless by something exerting a force in the opposite direction. They correctly calculate that the net speed of the object will be nothing and therefore there would be no airflow over the wings of the plane to allow it to take off.

i.e. If the plane applies no power and the belt moves -10 ft in one second, then the plane moves 0 + (-10) = -10 ft. However, if the plane applies power to move over the belt at +10 ft in one second, then you have +10 + (-10) = 0.

This assumes you are matching wheelspeed to belt speed which is one of two possible interpretations, the other that you match belt speed to ground speed which results in wheelspeed double the groundspeed.
In reality, both answers are equally valid depending on your point of view and how you interpret the question, which has been worded very badly (on purpose, I’m sure).

Which explains why this is a conudrum which having no looked is all over t'internet and not a straight forward question and answer.

that just melted my brain

 

[tim_enchanter]

I see what you mean...

Hang on, brain melting...

OK, gotten to the bottom of it....

YAY

 

[VIRII]

that just melted my brain

Hahahaha that looks like modern day O level physics and the "there are no wrong answers" approach to schooling.

 

[divine`]

However, the theoretical thinkers will ignore the real-world practicalities of the situation because it would never exist. Instead they abstract it to a simple object with a given speed, which is being kept motionless by something exerting a force in the opposite direction. They correctly calculate that the net speed of the object will be nothing and therefore there would be no airflow over the wings of the plane to allow it to take off.

This is where the argument arises, because the treadmill would never keep the plane motionless due to the fact that its wheels are free to rotate and as such transfer no forces or energy from the treadmill to the plane.

 

[blighter]

Hahahaha that looks like modern day O level physics and the "there are no wrong answers" approach to schooling.

there are no wrong answers in life, its either right or not right

its like you can never lose a race... you just don't win

 

[Macro]

The short vesion seems to be there is no right answer as the question is worded in a way that allows you to prove either result.

Purely from a practical point of view i'm inclined to go with the plane taking off ok, however if you look at the counter argument that also makes complete sense.

This is why it gets debated for hundreds of pages and ends up in arguements about tyre types, length of treadmill etc which are outside the scope of the question and so can be used to bolster either point of view without any actual relationship to the OP.

It is a silly thing...

 

[VIRII]

there are no wrong answers in life, its either right or not right

its like you can never lose a race... you just don't win

Gah modern day schooling, breeding a generation of illiterate, science deficient, mathmatically challenged people who aspire to mediocrity.
Last thing we need is more labour voters .....

 

[blighter]

Gah modern day schooling, breeding a generation of illiterate, science deficient, mathmatically challenged people who aspire to mediocrity.
Last thing we need is more labour voters .....

lol but i will never ever vote for anyone thats in my sig!
would you prefer right or caned, or right or not-right?

 

[VIRII]

They won't skid or lose grip - the wheels are free to rotate as fast as they like. The friction force (co-efficient of friction between wheels and treadmill multiplied by the reaction force, i.e. weight of the aircraft) would only come into play if the wheels were being driven or braked, and they aren't.

Then the plane would not move forward at all would it.....
However if we accept that the plane is indeed moving forward then the wheels are rotating, the treadmill is countering the rotation exactly according to the question so there will be skidding.
There is either skidding or the plane doesn't move.
The plane does move...

 

[divine`]

The short vesion seems to be there is no right answer as the question is worded in a way that allows you to prove either result.

You can only 'prove' the theoretical viewpoint by ignoring basic physical rules and principles though.

Then the plane would not move forward at all would it.....
However if we accept that the plane is indeed moving forward then the wheels are rotating, the treadmill is countering the rotation exactly according to the question so there will be skidding.
There is either skidding or the plane doesn't move.
The plane does move...

They wouldn't have to skid at all, because they free wheel they would just spin faster and faster until they reached an infinite speed.

However the bearings or tyres would most likely melt long before we hit infinity.

 

[VIRII]

lol but i will never ever vote for anyone thats in my sig!
would you prefer right or caned, or right or not-right?

Schoolies should be caned regularly anyway. Caned, detained and beaten.

 

[blighter]

Schoolies should be caned regularly anyway. Caned, detained and beaten.

thank god i'm a Collegie then lol i've just worked out i've been posting once every 4 minutes for the last 3 hours so i think i really should go before i get caned by Yemen/Spie

 

[VIRII]

thank god i'm a Collegie then lol i've just worked out i've been posting once every 4 minutes for the last 3 hours so i think i really should go before i get caned by Yemen/Spie

Colleges are just trendy left wing socialist places of experimentation anyway.
No real learning goes on there.
Ban colleges, grammar school till 16. Intelligent ones stay on for A levels, 3 years national service for the rest.

 

[tim_enchanter]

I see what you mean...

Hang on, brain melting...

OK, gotten to the bottom of it....

Nicked from elsewhere on t'internet

i.e. If the plane applies no power and the belt moves -10 ft in one second, then the plane moves 0 + (-10) = -10 ft. However, if the plane applies power to move over the belt at +10 ft in one second, then you have +10 + (-10) = 0.

This assumes you are matching wheelspeed to belt speed which is one of two possible interpretations, the other that you match belt speed to ground speed which results in wheelspeed double the groundspeed.

In reality, both answers are equally valid depending on your point of view and how you interpret the question, which has been worded very badly (on purpose, I’m sure).[/I]

The question states that the plane applies full power, none of this enough to do 10ft/s over the belt rubbish.
It all comes down to this does the plane in question have enough power to takeoff on a normal runway, if it does it can take off from from the treadmill.

 

[blighter]

Colleges are just trendy left wing socialist places of experimentation anyway.
No real learning goes on there.
Ban colleges, grammar school till 16. Intelligent ones stay on for A levels, 3 years national service for the rest.

i was at grammar till i was 16 and had the choice to stay on for a-levels, but i just see them as another 2 years of stuff you'll never necessarily use in your life, so i went to a more future-career-specified-route and i must admit, i don't regret not doing a-levels one bit (seeing that my course - a btec national - counts as about the same UCAS points etc as 3 A-Levels

lol @ tim for carrying on with the OT