The "Plane on a Treadmill" Question

[Flint]

Let's just read the question and decide what we're being asked about:

First, the plane "begins to move forward." So, forward motion is possible, although it isn't stated whether this forward motion is relative to the surface of the treadmill, or relative to the ground.

Next, the treadmill is described. It is "made to match the forward speed of the plane, only in the opposite direction." What the forward speed of the plane is relative to remains unspecified. The treadmill is said to "move backwards beneath the aircraft as the aircraft moves forward." What the forward motion of the plane is relative to remains unspecified.

Thus, when the treadmill is said to "match the forward speed" of the plane, it isn't stated how this speed is determined. When the treadmill is said to "move backwards...as the aircraft moves forward" it isn't stated how this motion is determined.

So, for step number one, to read the question and determine the parameters of what is being described, we cannot describe the treadmill because we cannot describe the plane, therefore we certainly cannot describe their relationship.

When Mythbusters tests this scenario, I will be curious to see what is tested. Because the question as stated here isn't something you can test.

[HungLikeJesus]

My point exactly.

[classicman]

For the record, the plane will not take off!

That is simply my opinion which is worth as much as you paid for it.










but I'm still right :p

[HungLikeJesus]

The plane will take off.

As Newton said to Edmund Halley, "I have calculated it."

[Happy Monkey]

Originally Posted by Flint

Next, the treadmill is described. It is "made to match the forward speed of the plane, only in the opposite direction." What the forward speed of the plane is relative to remains unspecified.

Right. That's what makes it a trick question. The first instinct of someone who knows how wings work is to assume that the spirit of the question is that the plane is held stationary. That assumption is not present in the question. Phage0070's wheel friction interpretation is the most grounded in reality of the ways to follow that line of thought, but even that requires the additional assumption of landing gear that can survive the friction (against the road, and internally on the bearings) required to counter an airplane engine, which would likely be several times the speed of sound.

The "relative to the ground" interpretation can actually be done with a real plane, so I'm guessing that that's the one the Mythbusters will do.

[Clodfobble]

Oh for Christ's sake... IT'LL BE ON IN JUST A FEW HOURS.


Just sit tight and wait, 'kay?

[lumberjim]

my prediction is that the Mythbusters episode will do naught but inflame the argument into further heretofore unrealized levels of ridiculousness.

[monster]

.

[tw]

Originally Posted by Flint

First, the plane "begins to move forward." So, forward motion is possible, although it isn't stated whether this forward motion is relative to the surface of the treadmill, or relative to the ground.

Go right back to Kitsume's post #1.

Originally Posted by Kitsune

A plane is standing on a runway that can move, like a giant treadmill. When the plane's engines throttle up, it begins to move forward, ...

That means the plane moves forward relative to air - independent and irrelevant to a treadmill.

Between plane and the treadmill are wheels. Wheels spin as slow or fast as necessary so that plane and treadmill remain completely independent of each other. Grasp the major significance of the word independent. Tread mill moving forwards or backwards will only affect how fast and which direction wheels spin. Tread mill will have no affect on the plane.

I am still completely mystified why this is not obvious to everyone. In post 104, Happy Monkey again and accurately answered. He is answering to others who remain confuse in post 196.

Meanwhile, the question was answered in maybe five different ways - all coming to the same conclusion - in post 152.

First - what is the purpose of wheels (landing gear)? Velocity of a plane is totally irrelevant to ground. Wheels will spin as slow or as fast as necessary so that volocity of the runway and velocity of plane stay totally independent.

Does not matter what speed or direction (a one dimensional problem) a treadmill moves. It is that simple. Some still have difficulty after 305 posts and 13 months later? I am completely baffled why something so simple has been made so difficult.

It's this simple. Wheels mean the plane is not affected by the treadmill (except by some trivial bearing resistance that is made 100% irrelevant by the planes jet engines). Wheels and jet engine means the treadmill can be replaced by a runway (a treadmill moving as 0 Km/sec) and have the exact same answer.

[TheMercenary]

And not a single comment about Bush, he must be drinking, he is slipping.

[tw]

Originally Posted by TheMercenary

And not a single comment about Bush, he must be drinking, he is slipping.

Wheels on a jet plane even make the Bushes irrelevant to the problem. In 356 days, even we will be independent of the bushes (which is really only a good place to pee).

[TheMercenary]

I knew your obsession would never leave you. Who are you going to talk about when he is gone?

[regular.joe]

I ran on a treadmill for about 35 minutes the other day, I did not move forward. Does it matter if it's me or a jet plane on the tread mill?

[classicman]

I am totally tailposting here, but.......

Isn't the issue the planes speed relative to the earth? If the plane is spinning on a treadmill, then it isn't moving at all relative to the earth. I must be missing something - lil help?

[classicman]

Originally Posted by Flint

No. No lift, as UT said. Planes do not take off from a stationary position. What would you expect it to do, suddently leap in the air? At what speed? From zero to what, in how many seconds? Same question: if you drop a paper airplane on the ground, will it suddenly leap in to the air and fly for no apparent reason? Same answer: No. The end.

Originally Posted by Flint

No! The engines (normally) move the plane forward to make air go across the wings and produce lift. No going forward, no lift, no take off.

Originally Posted by Flint

It's not already in the air, and it will never get there from a staionary position. The engines DO NOT "push" the plane into the air.

Originally Posted by Flint

No. The movement of air over the wings does it. No movement = no lift = it will not take off.

Originally Posted by Flint

Forget the wheels. The plane needs to move against the air to generate lift, to take off. It can't move against the air, so it can't take off.

Originally Posted by Undertoad