The answer is "yes, the plane takes off".

Discuss.

*IMPORTANT UPDATE*

The debate is now moot as its just been done in real life. However I'm going to leave the thread open so I can hear the whining of "ohhh the Mythbusters didn't do it right".

The plane takes off.

The plane takes off.

The plane doesn't take off!

Fookin' hell how big is this conveyor belt?

(The plane takes off, people who think otherwise seem to think the landing gear accelerates the aircraft)

The only way the conveyor belt would stop the aircraft is if it was moving so fast that there was such incredible friction in the bearings of the wheels on the gear that they melted and the plane ran into the ground because it couldn't support itself.

It's also probably physically impossible to build a conveyor belt that fast.

It will take off.

My father always told me:
An airplane doesn't drive, it rolls.

It's like a toy car at the grocery store. If you hold it still on the belt at the check out, it will stay put. And if you try moving it back and forth, it'll move no problem. The wheels will be spinning faster, but you'll have no problem moving it down the moving belt.

It's the same with your plane, except instead of your hand, it's a jet.

I demand that all who thought otherwise shamefully raise their hand.

The answer is no. The fact that the airplane isn't going anywhere means theres no air moving across and over the wings (therefore creating a high pressure on one side and low pressure on the other side.)

Lol amirite?

Kyle, you *******, this is the second time you've pulled this crap!

BombayZeus is indeed correct. No sufficient air movement over the top of the wings, no takeoff. Simple. It has nothing to do with propellors or turbines other than they provide the forward motion that grants the moving air.

[This is assuming, of course, that the conveyor belt is able to keep the ground speed of the airplane at zero. If the plane is still able to move forward, it can take off with enough air over it's wings. I make this assumption because it's a stupid question without it and the conveyor belt is moot.]

Steven, the plane moves forward as it normally would, therefore it takes off.

Then why even ask the question? If the airplane still moves, there is no need to even involve the conveyor belt in the situation.

"Suppose you want to have sex but don't want to get anyone pregnant, so you wear a condom. But then you never have sex. Did the condom work?"

The question exists to force people to think about what's actually going on rather than what at first seems obvious. It's the kind of question you get in highly-contested academic and job interviews.

In my interview for Cambridge I was asked this question:
Assume you are on the equator standing over a hole drilled straight through the earth to the other side. Also assume that the hole is completely clear and the heat of the core isn't enough to melt a spherical object you have that fits easily insie the hole.
You drop the object down the centre of the hole, describe what happens to the object.

I understand why the airplane will take off. Physicists often invent silly questions with unreal situations (like your equator question); I thought in this case the conveyor actually did stop forward motion on the plane. Of course it takes off.

Also, the object will fall into the hole, swing back and forth for a while when it reaches the center, until finally stabilizing in the exact center (unless it gains enough speed on the "downward" journey to break free of gravity and exit the atmosphere on the other end).

The ball will hit the side and slow down fairly quickly, no chance of it reaching the other side.

From my limited understanding of gravity, wouldn't the exact center of the Earth's gravitational pull shift if a hole were cut through where it originally was located?

[Edit: Removed due to my own stupidity and humiliation stemming from it.]

i agree with Steven and Bombay Zeus. The plane doesnt take off.. The entire concept of how an aircraft flies relies on movement of air over the wings, not the forward movement of the plane itself. The plane described in this situation would be sufficiently stationary. its just like the tests where a car is placed on the metal rollers and the wheels turn as if the car were going forward, but it stays in one spot. This is the same concept. Therefor since the plane would be basically stationary, no air is going over the wings (save for maybe a propeller driven one blowing air back)so no lift and thus no flying.

The thrust of the engines is not applied through the wheels, ergo it WOULD take off, no matter what speed the conveyor belt is moving, it's not going to have a substantial effect on the speed of the airplane.

If it were a CAR on the conveyor belt, no it wouldn't continue, but an airplane would, the forward acceleration of the plane is not relative to the speed of the ground.

Edit: The only way you could prevent a take-off of a plane would be to stop the flow of the air around it.

No.

Well, then I'd assume it assumes the position in the very center of the Earth's gravitational pull. Of course, without knowing how gravity works, I'm almost guaranteed to be wrong.

That, and the gravitational pull will lessen the closer to the center you get, and you have to factor in terminal velocity.

For those that continue to have issues comprehending this, try this:

Get a model airplane, and stick it on a treadmill. Tie a string to the front of the airplane, and tie it to the front of the treadmill. Start the treadmill up.

Now, start pulling in the string. Regardless of how fast you make that treadmill, that plane is going to move foward.

The thrust from the jet engines is analogous to the string being pulled. The thrust pushes the jet, it does not make the wheels spin.

Detty, the ball hits the side because of the rotation of the Earth, yes?

thats weird, I was looking at the first of these threads earlier today 0_o

When you throw a ball straight into the air, does it curve when it comes down? No.

That's how i always looked at it, and ultimately the only force that would prevent forward motion would be friction from the wheel berings. People are thinking cars when they are trying to visualize this problem.

Right, the only effect the conveyor has is that the wheels are spinning twice as fast as usual during take-off.

The conveyor is irrelevant. The force comes from the thrust of the jet, not from the torque of the wheels. Imagine you were pushing a hot wheels car down a conveyor belt going 500mph. Singe you aren't pushing against the belt to go forward it's just as easy as if it was still. However if the car an electric engine in it, it would have to be really powerful to even stand still.

The key here is, because the force down the ramp is not coming from the torque against the belt, the belt can't spin fast enough to keep the plane still.

This topic propagated a great flame war about a year ago.

Wow. It would appear that some of you have not taken high school physics or failed it miserably. Lemme tell you why the plane will take off. Newton's 3rd law of Force. The props/jets will propel air backwards, this will make plane move forward. These are analagous to rockets. Too many of you are thinking that the plane moves forward on the ground because the wheels themselves propel the aircraft. Nope. It is the prop/jet that taxis the aircraft on the tarmak. So like CoolMatty said, that plane is going to roll off the conveyor belt and take off.

Draw a sodding force diagram people!

It literally hurts my head when people try and explain why the plane will not take off.

Visualize it like this, if it helps. Imagine the wheels on the plane aren't wheels at all, but hover pads. All they do is keep the plane off the ground.

Yes. Well, depending on your frame of reference. Coriolis effect and all.

Are the airplane's brakes engaged? D:

I don't understand. There is no air flow over the wings. No air = no lifty?

Yes, there IS airflow, from the forward movement of the airplane! Once the engines turn on, the plane is NOT stationary. It will not stay in the middle. It will move forward, regardless of what that conveyor does.

The good news is that every time we have this thread, we seem to have fewer people insisting the plane won't take off.

It generates much lulz.

Oy vey, both sides can be right depending on a few things that AREN'T mentioned. 1) are we assuming that the wheels are 100% friction free (and in neutral)? Cause that's the only way the conveyor won't have any effect on the plane's position. You're assuming the breaks aren't on, since if they were on, then you'd have the frictional force of the plane on the ground to consider.

Now that I've said that... for a plane to have enough thrust to normally take off, it would most likely be easily overcoming any frictional force caused from the wheels, so yes, it would take off, though it'll probably require a slightly higher amount of force from the propellors than on a stationary runway.

Now here's another "mind-question" that you can actually try. Get a small wheeled object and put some sort of fan/propeller on it that's barely strong enough to make it move. Place this on a piece of paper, and once it starts moving, gentily pull the paper in the opposite direction. You may find the results surprising at first (the plane "should" stay relatively still with respect to the actual ground) but there's an easy explanation: the force caused by friction on such a small object is significant when compared to a small propeller. But on a big plane, that friction would be very insignificant.

I hope this cleared things up for those of you still confused why people say it will move. If not, I can make up more things off the top of my head and see if any of them are to your satisfaction

:suicide::suicide::suicide:

The turbines are what moves the plane forward. The wheels have nothing to do with it.

I don't know why I keep clicking on this thread when I know it will just upset me.