Airplane / Treadmill Voting Booth

[focus]

Focus, just to be clear w/o reading the entirety of the other thread: you do think the plane will take off correct?

Plane takes off. A car on the same treadmill moves forwards more or less normally. Has nothing to do with overcoming friction/how the force is applied/etc. The question dictates that forward motion is necessary in order for the treadmill to move backwards. That would mean that if the plane is actually standing still, the treadmill is not allowed to move either. The jet engines, or car engine, would be putting force down like a motherfucker and nothing would be happening. This is not good physics, I'm pretty sure.

[maniloff]

What boggles my mind is that, with all that education, you are incapable of reading the question correctly.

Hey, I was a former hacky pseudo-physicist. I didn't say I could read good.

[DJSapp]

Hmmm, one out of three maggots is an idiot.

Sounds about right.

[summit]

For those morons who think that thhe treadmill accellerates infinitely and holds the plane motionless relative to the ground while its wheels spin (which it does not, the question precludes this), as the treadmill reaches a high enough speed, air resistance will cause the treadmill to generate a wind which will eventually approach a speed which will eventually allow takeoff even in your fruity world.

(yes it will be flying with an indicated airspeed of 150 knots, an indicated groundspeed of... well thats impossible to calculate in this insane twisted version of reality... a true groundspeed of zero (up until the point of takeoff then the plane accelerates)

in this twisted world the plane may stall if it doesn't accelerate suficiently before leaving the generated wind effect zone of the treadmill... but it will take off

[Viva]

air resistance will cause the treadmill to generate a wind which will eventually approach a speed which will eventually allow takeoff even in your fruity world.

But in a fruity world there wouldn't be any fruit resistance and that just messes all the equations up.

[DJSapp]

But in a fruity world there wouldn't be any fruit resistance and that just messes all the equations up.

Actually, wouldn't the fruit get sucked into the engine and blow the plane up?

Damnit, I need to change my answer now.

[summit]

actually as the wind increases (though still below takeoff speeds), the lift force increases (though still below g*M) decreasing the normal force decreasing the effectiveness of the treamill causing it to have to go fast causing it to generate even more wind (exponential effect)

But in a fruity world there wouldn't be any fruit resistance and that just messes all the equations up.

don't tell them that the treadmill can have 0 effect on the airplane in the absence of friction. it will ruin their whole day!

[focus]

For those morons...

Earlier in this thread you posit that a car would remain stationary. Have you seen the light? Or are you still...a moron?

[huck4bucks]

Holy cow, it simply boggles the mind that otherwise intelligent people don't think that the plane will take off.

It's no coincidence that the smart people think the plane will stay on the ground.

[summit]

Earlier in this thread you posit that a car would remain stationary. Have you seen the light?

Yep... you are one of those morons

I've shown that under both interpretations of the question

1. Treadmill speed = aircraft speed
2. Treadmiill speed = whatever speed is required to generate enough friction to keep the aircraft stationary relative to the ground

that the aircraft still takes off

[focus]

OK. So you do indeed acknowledge that the car would move on this treadmill?

Just trying to cull the retards from the smart people...

[Tippster]

The car would not move in relation to its point in space on this treadmill, since the car cannot move independently of its wheels. There-in lies your fallacy, regardless of which hand is which.

A car moves its wheels which "move" the ground. The plane moves the air, regardless if it's on the surface or in the air.

[focus]

The car would not move in relation to its point in space on this treadmill, since the car cannot move independently of its wheels. There-in lies your fallacy, regardless of which hand is which.

A car moves its wheels which "move" the ground. The plane moves the air, regardless if it's on the surface or in the air.

You're in the car, you hit the gas. The car moves forwards, the treadmill moves backwards at the same time the car moves forwards, at the same speed. If the car doesn't move forwards in relation to its point in space on the treadmill, the treadmill cannot move backwards!

The forward speed of the car, in relation to its point in space on the treadmill, will always be 1/2 of the rotational speed of its wheels. The car's acceleration, in relation to its point in space on the treadmill, will always be 1/2 of that of its wheels. But the car WILL accelerate. It WILL move forwards (in relation to its point in space).

[Brock Landers]

The car would not move in relation to its point in space on this treadmill, since the car cannot move independently of its wheels. There-in lies your fallacy, regardless of which hand is which.

A car moves its wheels which "move" the ground. The plane moves the air, regardless if it's on the surface or in the air.

This is what they do when testing emissions. They put your car on a pseudo treadmill, only contacting the wheels, and drive the car. Of course it doesnt go anywhere, its all done in a garage. Car powers wheels. Wheels spin. Treadmill spins in the equal and opposite direction.

Not the same as the plane though, where the wheels do not provide the forward motion (not saying you said this, im just saying...)

[focus]

Car powers wheels. Wheels spin. Treadmill spins in the equal and opposite direction.

Not the same as the plane though, where the wheels do not provide the forward motion (not saying you said this, im just saying...)

In your garage the treadmill matches the speed of the wheels. In our scenario the treadmill matches the speed of the car. Two very fucking different things!

[summit]

You're in the car, you hit the gas. The car moves forwards, the treadmill moves backwards at the same time the car moves forwards, at the same speed. [I][B]If the car doesn't move forwards in relation to its point in space on the treadmill, the treadmill cannot move backwards!

This is insterpretation #1 above for the airplane and under that interpreation the airplane takes off.

[focus]

Remember, the track is not at a fixed velocity, it accelerates along with the wheels.

This is where so many of you are so confused. It accelerates along with the car. It could give a shit about the wheels.

[ICEHOCEY77]

It takes off.



until the treadmill activates the bomb placed in the forward cargo hold, end result, the plane crashes



+1 to the treadmill.

[summit]

This is where so many of you are so confused. It accelerates along with the car. It could give a shit about the wheels.

I thought you were an interpretation #2 type of guy? (either way the airplane flies)

Under interpreation #1 the car should move (and the airplane flies)

Under interpretation #2 the car should not move (and the airplane flies)

[focus]

I thought you were an interpretation #2 type of guy? (either way the airplane flies)

I'm a #1. I can't figure out what the hell you are.

In reality, the car would probably move a couple of mm.

Remember, the track is not at a fixed velocity, it accelerates along with the wheels.

Unless you've recanted these and other related statements.....

[summit]

I'm a #1. I can't figure out what the hell you are.

It doesn't matter! The airplane takes off anyway!

(unless the tires blow out)

but I interpret the question under #1

[DJSapp]

A car is sitting on a runway that can move (some sort of band conveyor). The car MOVES in one direction, while the conveyor moves in the opposite direction. This conveyor has a control system that tracks the cars speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction).

The problem is quite clear that the speed is not measured by a speedometer at the wheel. It would be measured by a radar gun set on the ground. The problem states that the car (yes, the whole fucking thing) MOVES in one direction. At a dyno shop, the car as a whole does not move. This is the difference.

[orlowskij]

I wasn't going to post, but I think this is a clear way to illustrate what is going on.



It simplifies the problem a lot if you draw a FBD of the plane and the wheels. The only forces that act on the body of the plane (the part that determines whether or not it takes off) are the normal force upward from the treadmill, the force of gravity downward, and the thrust of the engines forward. Assuming that there is friction between the wheels of the plane and the treadmill, and that the friction in the wheel bearings/rolling resistance of the plane is negligible, the plane will take off. When the pilot throttles up the engines, the plane will start to move forward, the treadmill will spin, the wheels will spin, and the plane will continue to accelerate relative to the ground until it takes off. The treadmill just means that the wheels will be spinning faster when it does take off.

[focus]

pay attention, orlowski. That illustration is not what's going on, here. In that illustration the rollerblade wheels are spinning, and the guy isn't moving forwards. Impossible in terms of this question.

Read DJ's post above yours.

[lemon boy]

pretty sure that the illustration is meant to show that dumbass exhibit #1 is about to get his ass dragged off the treadmill