A harmless little riddle

I was going to mention the Harrier Jump Jet, but decided against it- people are confused enough as it is.

To tackle your statement of the treadmill being set to an incline- the same principles apply to this as the previous examples- if the jet is creating enough force to propel it fowards at 150mph, the treadmills 150mph in the opposite direction will still negate it. The tricky part of your statement is that the force from the jets will be hitting the ground but at the end of the day the teadmills motion will negate any speed the plane produces.

Seriously I'm not trying to hassle you but if the treadmill is moving clockwise the airplane's wheels will be moving counterwise(Relative to the observer).

But my real question is why are you getting so angry and hostile about all this? Why all the uppercase writing and all the "asshole" and F***ing brilliant and moron comments.

What gives? Is this your posting persona where you blow off some steam but you're not otherwise like that.

I don't believe you.

The airplane WILL fly. the wheels and wheel-treadmill interface have nothing to do with it. the propellers are acting on the air, not the treadmill.

at take-off speed the plane will be moving relative to the treadmill at twice the speed relative to the ground.

this is a tricky problem because it says that the treadmill moves at the same speed relative to the plane which tricks us into thinking that the plane causes the treadmill to move by the wheels pushing off on it. that is not the case. there is no appreciable friction between the wheels and the treadmill because the wheels are passive. a cars wheels on the other hand would push off of the treadmill.

this example should convince all of you: imagine that instead of a plane, we are talking about a person. a person on roller skates. and this person on roller skates is standing on top of the same treadmill. in front of the treadmill a rope is tied to a wall and extends back to the person. the person picks up the rope. when the person pulls on the rope, because the rope is tied in place, they move towards the front of the treadmill. at the same time the treadmill is programmed (important to note, because if it was just based on friction the treadmill wouldnt move much at all), it is programmed to move backwards at the same speed the person moves forwards. what would happen is the person would actually move forwards relative to the ground, with the wheels of their rollerskates moving at twice that speed over the treadmill. otherwise you are saying that you'd never be able to pull yourself forward.

The plane is attached to a rope???

The trick here is thae assumption that the plane is sitting on an enormous treadmill. Or at least could exit the treadmill.

As "It Will Fly" suggests, we can say that the force created by the engine thrust is akin to a pulling force, like having a rope attatched to the plane and pulling it towards the front of the treadmill (with a crank of sorts) with a force equal to the thrust. Neglecting the loss of energy due to friction, the treadmill is spinning the wheels of the airplane and is not significantly counteracting the force of the thrust. No matter what speed the treadmill is set at, it won't create a force great enough to stop the plane from moving forward realtive to the ground. This forward motion is enough to generate lift and the plane will take off. If it moves off the front of the imaginary treadmill, it will simply continue forward motion until sufficient lift is generated.

It will move forward relative to the ground, and thus will take off.

Wheels on a plane are just there (in takeoff) to help alleviate losses of energy due to friction.

. wrote:

The plane is attached to a rope???

no you moron. but instead of pulling on a rope, say you were pulling on air. which is what jet engines do. same difference. you are acting on something other than the treadmill. obviously air is going to give more than a rope so it is less efficient than pulling on a rope but that is only a difference in quantity not principle.

I was joking. The example you presented may convince some people, but I am still going to argue.

The treadmill is going to completely negate all foward action of the plane, so no matter what speed the plane moves, its speed relative to the air is still going to be 0mph.

the riddler wrote:

An airplane is sitting on an enormous treadmill. As the plane starts its engines, the treadmill runs in the opposite direction at the same speed the plane is moving. Can the plane take off?

The plane will fly. The riddle says that "the plane is moving." The treadmill is a red hearing as it does not affect the plane's movement.

This experiment has actually been done. The plane takes off. I don't really care if anyone believes it or not, but those who don't think it will take off are wrong. The main reason is, as others have mentioned, is the fact that all other things balancing out, the atmosphere is stationary. Bitch and moan all you want, whatever. The plane is capable of flight in this situation. Also, kudos to whoever it was that had that link to the 1/4 mile time thread on myspace. funny stuff.

Read the question again. And again. And again.

The plane will NOT be moving relative to the air= no takeoff.

THE PLANE WILL ABSOLUTELY NOT TAKE OFF

THE ONLY THING MOVING IS THE WHEELS, THE PLANE IS STATIONARY, THERE IS NO AIR MOVIGN OVER THE WINGS TO CAUSE LIFT

IF IT TOOK OFF, THE PLANE WOULD STILL BE MOVING AT 0 MPH RELATIVE TO THE GROUND, ITS NOT RANDOMLY JUST GONNA LIFT OFF AND START MOVING 150 MPH AWAY FROM THE TREADMILL

ANYONE WHO SAYS YES IS A RETARD

NOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

ID BET MY LIFE ON IT

Build a Bridge out of it.

The plane isn't stationary. The treadmill belt does not keep the plane from moving forward. Its fairly straightforward.

If you could keep the plane from moving forward relative to the ground, then it would not take off. But that would require a force equal to the thrust, in the opposite direction, on the plane body.

Of course the riddle presents a logical paradox if you believe that the plane is still. If the plane is traveling at zero mph, then the treadmill must be going at zero mph.

The plane's engines are producing thrust, so it would be moving forward.

The only possible solution is that the planes's movement is not altered by the treadmill, although the treadmill's movement is altered my the plane.

-You would bet your life that the plane would not takeoff.

-You hold a facetious belief, because you did not read the thread (or you are an imbecile; I will assume the former).

Therefore, I can conclude that you can't read to save your life.

It can't take off, it's very simple.

Here, we'll try this one more time.

Everyone agrees that a plane moves forward because of its engines, right? This much is obvious.

When it's moving through the air, up in the sky, it's because of the engines. When it's on the ground, it moves because of the engines - those little wheels don't have any power going to them. They just spin. Can we agree on that much?

From there, let's say the plane starts to move on the treadmill (which hasn't started yet). Is it the engine or the wheels pushing it forward? The engine, of course. The wheels are just spinning. Once the plane gets fast enough, we don't even need the wheels any more.

Heck, to visualize this one, let's pretend the wheels aren't even on the plane. Let's just say the plane is hovering above the ground. Can it still go forward? Yes, because of the engine. Will the treadmill affect it? No.

Now let's pretend we're hovering above the ground and start to move forward. Now what if we hung down off the bottom of the plane and touched an extra wheel to the ground. It's gonna spin like crazy, but that's all it will do.

The treadmill has no effect. The plane can still take off.