Then I page 6 Joe said
I said well done Joe you just hit the jackpot.
Since then Joes been trying to persuade everyone the question is invalid.
The plane wont take off Joe as any movement is impossible.
conveyor belt and plane answered at last ??
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Then I page 6 Joe said
I said well done Joe you just hit the jackpot.
Since then Joes been trying to persuade everyone the question is invalid.
The plane wont take off Joe as any movement is impossible.
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You have repeatedly failed to answer my question.
Do you agree the question trazor posted is essentially the same question as the one in the link I posted above?
And if not, why not?
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They're trying desperately to counteract the motion of the belt which is cancelling out the action of the wheels thus rendering the plane motionless.
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If you mean this question then yes it's the same as Trazor's.
And the answer is the same.
You can go find the biggest most powerful engine in the universe or a dinky toy from woolworth, you still can't match the wheel speed with the plane if the conveyor and plane are moving in opposite directions.
What wheel speed? The wheels are on a bearing. They rotate. That does not imply the aircraft is moving in any direction.
The engines push against the air. As a result of this, the aircraft moves relative to the air. What the ground under it is doing means nothing, because it's not tied to it.
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The wheel speed is unimportant!
You may argue the wheels will be travelling twice as fast as they would if the plane was on tarmac, but it will not prevent take-off.
When thrust is applied to the engines, that plane (to which the engines are attached) will move forwards and lift off.
As Monkeh is implying, the engines are pushing against the air, nothing to do with the wheels.
Quote:
So what does this all have to do with treadmills? Well, now let's place our plane on that treadmill and see what happens. If the wheels were perfect - that is, there is no friction in the bearings (and no deformation of the wheels as they spin) - then something interesting happens. When we turn on the treadmill, the plane stays stationary on its own. The wheels simply spin along the track, and impart no force to the plane. If you had a car with frictionless axles, and you disconnected the whole drive train, the same thing would happen to your car.
The only reason that a plane or a car moves backwards on a treadmill is that the wheels are somehow partially locked to the axles. In a plane, this is because of minor friction in the bearings. In a car, it's because of the drive train. If you want the car to stay still, you have to turn the drive train at the proper speed. If you want the plane to stay still, you have to overcome the minor bearing friction. And again, since friction does not change with speed, you don't have to exert any more force at higher speeds. If you run the treadmill at 5mph and turn on the plane's engines just slightly, they will provide enough thrust, pushing against the air, to keep the plane still. If you then increase the treadmill speed to 500 mph, you won't need to adjust the throttle on the airplane - it will remain stationary. That's because it's seeing the same frictional force that it was at 5mph. Thus, it doesn't matter how fast the treadmill is moving - if the pilot does not want to remain stationary, then he won't. It only uses the very first bit of power from the engines to keep the plane stationary. As the throttle is increased from that point, it moves forward just as it would on any other runway. It's pushing against the stationary air!
Edit: I was still typing as Monkeh posted his response. Slowcoach that I am...
You may argue the wheels will be travelling twice as fast as they would if the plane was on tarmac, but it will not prevent take-off.
When thrust is applied to the engines, that plane (to which the engines are attached) will move forwards and lift off.
As Monkeh is implying, the engines are pushing against the air, nothing to do with the wheels.
Quote:
So what does this all have to do with treadmills? Well, now let's place our plane on that treadmill and see what happens. If the wheels were perfect - that is, there is no friction in the bearings (and no deformation of the wheels as they spin) - then something interesting happens. When we turn on the treadmill, the plane stays stationary on its own. The wheels simply spin along the track, and impart no force to the plane. If you had a car with frictionless axles, and you disconnected the whole drive train, the same thing would happen to your car.
The only reason that a plane or a car moves backwards on a treadmill is that the wheels are somehow partially locked to the axles. In a plane, this is because of minor friction in the bearings. In a car, it's because of the drive train. If you want the car to stay still, you have to turn the drive train at the proper speed. If you want the plane to stay still, you have to overcome the minor bearing friction. And again, since friction does not change with speed, you don't have to exert any more force at higher speeds. If you run the treadmill at 5mph and turn on the plane's engines just slightly, they will provide enough thrust, pushing against the air, to keep the plane still. If you then increase the treadmill speed to 500 mph, you won't need to adjust the throttle on the airplane - it will remain stationary. That's because it's seeing the same frictional force that it was at 5mph. Thus, it doesn't matter how fast the treadmill is moving - if the pilot does not want to remain stationary, then he won't. It only uses the very first bit of power from the engines to keep the plane stationary. As the throttle is increased from that point, it moves forward just as it would on any other runway. It's pushing against the stationary air!
Edit: I was still typing as Monkeh posted his response. Slowcoach that I am...
Lots of mistakes there Securesparks.
The wheels are very important.
The wheels be twice as fast and No, it won't prevent take-off but then I never said it would.
Agreed the plane will lift off but the wheels wont match the belt speed.
we know how to fly a plane thanks, and if you take the wheels off my Piper Cherokee you'll realise just how important they are.
Put the plane on the conveyor belt the plane will not stay stationary without a force holding it in place, this is where myth busters failed because the weight of the plane was on the ground and not a conveyor belt. try it at Tesco's next time you go shopping.
Nope the plane will go backwards with the belt (with free wheeling wheels) and they wont be turning.
The wheels are very important.
The wheels be twice as fast and No, it won't prevent take-off but then I never said it would.
Agreed the plane will lift off but the wheels wont match the belt speed.
we know how to fly a plane thanks, and if you take the wheels off my Piper Cherokee you'll realise just how important they are.
Put the plane on the conveyor belt the plane will not stay stationary without a force holding it in place, this is where myth busters failed because the weight of the plane was on the ground and not a conveyor belt. try it at Tesco's next time you go shopping.
Nope the plane will go backwards with the belt (with free wheeling wheels) and they wont be turning.
Just for you Monkeh, lets call the conveyor belt the ground albeit moving.
Now take you plane and put it on the belt but tie the plane to a tree to stop it going anywhere. ok so far
Start the belt at 10 mph, and if you had a mileometer it would be reading 10mph as the wheels wizz along the road/belt.
Next untie the plane and start the motor, the plane will now move along the belt/through the air at 10mph as well as the belt doing 10mph in the opposite direction. the mileometer is now reading 20mph. remember the wheels are still on the road/belt.
Proof if you need it, a line on the belt will travel west, 10 miles & 10mph, the plane will travel 10 miles east & 10mph, or a combined distance of 20miles the wheels have done the full trip.
Right, so, because I haven't read all 25 pages of nonsense, I was entirely ignorant of whatever point you were badly trying to make which has no relevance whatsoever to anything.
This thread, just like the 'problem' of a plane on a conveyor belt, is intensely pointless..
I've also said that a few times as well.
It's supposed to be a thinking thread apparently. You make up a few scenarios, and ask whether the plane will take off within the parameters of the question.
Here's one:
Helicopter on a turntable which rotates at the same speed as the main rotor in the opposite direction.
Obviously physically not going to happen. Also obviously not going to take off.
Who thinks up these things anyway?
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I think we will just have to agree to disagree on this one, as no one on either side is budging!
No hard feelings!
How about we move on to that question about the pint glasses?
No hard feelings!
How about we move on to that question about the pint glasses?
I think we will just have to agree to disagree on this one, as no one on either side is budging!
No hard feelings!
How about we move on to that question about the pint glasses?
Someone want to fill me in on what you two are arguing about?
Because so far, I see what he's saying. Not that it's relevant to anything.
But that is the point it isn't meant to be relevant to anything.
Try this in the head please calculators not allowed.
1000 add 10, add 1000, add 20, add 1000, add 30, add 1000, add 40.
how many you got.
in real life 9/10 will say 5000.
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