Airplane on a Conveyor conundrum

[dieselboy]

I can't believe it took you 380 posts to understand the question and then you still got the answer wrong. I can't stop laughing. That's genius.

i never wrote 380 posts, come on

[dieselboy]

Ignore the ground and the conveyor, what happens?

the plane falls through to australia

[Slugsie]

yes but it has nothing to do with this question.

and why measure everything the same speed as the ground now? thats not what it says in the question..

if this were the case, then the plane wouldnt take off at all.
the plane wouldnt take off because there would be no wind to lift the wings, this is because the plane doesnt move. this is because the conveyor is goin one way at x speed, and the thrust is enough to keep it stationary to the ground.
this explanation has nothing to do with this at all

Er, no, where does it state that the thrust is enough to keep it stationary to the ground? The aircraft is attempting to take off. So it'll be using enough thrust to (try to) do that.

Remember, the conveyor matches the plane, not the other way round.

[Slugsie]

How fast is Tescos going?

AAaaaaargh!

(runs away and cries)

[BUSHWHACKER]

Haven't you people got jobs to do?

[nero279]

the plane falls through to australia

good answer.....




.....still incorrect though

[Slugsie]

Haven't you people got jobs to do?

Nope.

Haven't you got a V8 to fit and get working?

[BUSHWHACKER]

Nope.

Haven't you got a V8 to fit and get working?

Oh yeah, back in a tick!

[dieselboy]

Nope, if you do it that way then you are measuring your speed relative to the ground, and tescos speed relative to you. That has never been the case with this question.

NO NO NO!
if your measuring the speed relative to the ground, then you will see that the car is going 10mph to my left and tescos 10mph to my right = 20mph. (but tescos dont move but in your theory your saying it does)
dont add the two together! because tesco is stationary ALWAYS, relative to the ground the car is going 10mph. period.

It would be more accurate to say you are driving down the northbound carriage way of the M6 at 70mph. The copper in the southbound carriage way is also doing 70mph. You pass each other at 140mph. Do you have even a slight worry that you'll be done for speed at 140mph?
but this is two things approaching each other. when two objects approach, they have a total speed. this means you add the two together like you have done.
but the plane is travelling away from the conveyor. so you would subtract = 0mph always.
but anyway, because the plane goes 10mph away from the ground, this means that the ground is like its going the other way at 10mph (or -10mph)

its one or the other, dont add the two.

if you got on a kiddies roundabout, when your on it you would say that everyone is going round you, but when your off it you can clearly see that the roundabout is turning.

you dont add the two speeds together and get double.
.

:/

[dieselboy]

Haven't you people got jobs to do?

yes, and i will probably get a bollicking soon

[Sancho]

Dieselboy, this is a wind-up isn't it?

[Slugsie]

:/

Look, forget Tescos. We're not talking about an object that can't move, we're talking about an object that not only can move, but actively does so in response to another object moving.

OK, imagine this....

You're standing at the side of a runway. The runway is made up of a conveyor. On the runway is an aircraft that has a takeoff speed of say 30mph. Directly under the centre of the aircraft a mark is placed on the runway. The aircraft powers up, and moves off to your left, quickly gaining a speed (relative to you) of say 10mph. In response the conveyor belt surface moves off to your right matching the speed, so the mark moves off to your right at a speed of 10mph. That is a simple re-statement of the original problem.

Now, the aircraft is moving at 10mph, but it and the mark on the conveyor belt are moving apart at 20mph. The thing is, that that 20mph is irrelevant to the aircraft. So the aircraft accelerates to 20mph. So does the conveyor. They're now (the aircraft and the mark) travelling apart at 40mph. But again, that 40mph is irrelevant to the aircraft. So the aircraft accelerates to 30mph. So does the conveyor. They're now moving apart at 60mph. The aircraft has achieved it's take-off speed, so it does.

Case closed.

[dieselboy]

Look, forget Tescos. We're not talking about an object that can't move, we're talking about an object that not only can move, but actively does so in response to another object moving.

OK, imagine this....

You're standing at the side of a runway. The runway is made up of a conveyor. On the runway is an aircraft that has a takeoff speed of say 30mph. Directly under the centre of the aircraft a mark is placed on the runway. The aircraft powers up, and moves off to your left, quickly gaining a speed (relative to you) of say 10mph. In response the conveyor belt surface moves off to your right matching the speed, so the mark moves off to your right at a speed of 10mph. That is a simple re-statement of the original problem.

Now, the aircraft is moving at 10mph, but it and the mark on the conveyor belt are moving apart at 20mph. The thing is, that that 20mph is irrelevant to the aircraft. So the aircraft accelerates to 20mph. So does the conveyor. They're now (the aircraft and the mark) travelling apart at 40mph. But again, that 40mph is irrelevant to the aircraft. So the aircraft accelerates to 30mph. So does the conveyor. They're now moving apart at 60mph. The aircraft has achieved it's take-off speed, so it does.

Case closed.

but thats not what happens mate.

ok i will try to make it as simple as possible, like what you have done. ill re-explain the scenario you outlined in your first post. with a takeoff speed of 30mph like what you have said also. ok...

plane on a runway, with a massive conveyor.
the planes speed is measured by a fixed point in the ground.
the conveyors speed is always that of the planes but in the opposite direction. eg its always a negative of the planes speed.
planes take off speed is 30mph

the plane accelerates up to 10mph. this is measured by the fixed point on the ground. all the time the plane is accellerating the conveyor sees this and is always a negative of this speed.
but since the plane is moving away already therefore the conveyor is already moving away from the plane. so now we have a plane that is going 10mph away from the conveyor, and the conveyor has matched this the opposite way. but the conveyor hasnt turned or moved a fraction at all. but its still moving away from the plane at 10mph.

so;
now we have a plane that is 10mph relative to the ground
a conveyor that is -10mph relative to the plane
the ground that is not moving
and a conveyor that is not moving because the conveyor and ground are both going the same speed.

this happens all the way to 30mph and the plane takes off.

now when you read you explanation, you see your numbers get muddled up, and dont equate.
and you see that mine dont do that.

[dieselboy]

Dieselboy, this is a wind-up isn't it?

i thought you was trying to yes

[Chillitt]

[QUOTE=dieselboy;409760]but thats not what happens mate.

ok i will try to make it as simple as possible, like what you have done. ill re-explain the scenario you outlined in your first post. with a takeoff speed of 30mph like what you have said also. ok...

plane on a runway, with a massive conveyor.
the planes speed is measured by a fixed point in the ground.
the conveyors speed is always that of the planes but in the opposite direction. eg its always a negative of the planes speed.
planes take off speed is 30mph

the plane accelerates up to 10mph. this is measured by the fixed point on the ground. all the time the plane is accellerating the conveyor sees this and is always a negative of this speed.
but since the plane is moving away already therefore the conveyor is already moving away from the plane. so now we have a plane that is going 10mph away from the conveyor, and the conveyor has matched this the opposite way. but the conveyor hasnt turned or moved a fraction at all. but its still moving away from the plane at 10mph.

so;
now we have a plane that is 10mph relative to the ground
a conveyor that is -10mph relative to the plane
the ground that is not moving
and a conveyor that is not moving because the conveyor and ground are both going the same speed.

this happens all the way to 30mph and the plane takes off.

now when you read you explanation, you see your numbers get muddled up, and dont equate.
and you see that mine dont do that.[/QUOTEYou are doing this on purpose, aren't you. come on admit it!!!