Weird scientific questions

[blackdevil0742]

blackdevil, you just can't get the car syndrome out of your head, right? Maybe you should take somethings by faith.

I'm not thinking as if the plane was a car(I did it in my first post though)..i don't even care about the wheels or friction. The plane has the power to move forward but it will not lift.

[Espadon]

And you're right if the plane is not moving forward at its takeoff velocity. Which it has the full capability of doing.

Let's look at it this way: The wheels effectively "neutralize" any groundspeed that is moving in the opposite direction (once a certain speed threshold has been crossed, which has been established, since the original questions states that the aircraft's engines are already engaged).

The only scenario in which an aircraft can take-off-then-crash is if the treadmill is moving WITH the aircraft. I know it sounds really counter-intuitive, but what's happening is that the aircraft is moving faster than the engines are actually carrying it, and so will take off before the engines have achieved enough thrust to keep the aircraft aloft on their own.

[KorrupT MerC]

if i remember correctly, this topic was a debate topic meaning all aspects of the question are gonna be brought up, no matter how stupid they may be, thats the whole point of a debate, one brain vs another...

[LtKillroy]

blackdevil, you just can't get the car syndrome out of your head, right? Maybe you should take somethings by faith.

I'm not thinking as if the plane was a car(I did it in my first post though)..i don't even care about the wheels or friction. The plane has the power to move forward but it will not lift.

Point taken espadon, continue with your knowledge.

[Espadon]

Looking back, I think the original question should be rephrased so that it asks whether or not the aircraft will take off at (or near) the speed at which it will take off had it been on stationary ground. That would clear up the point blackdevil is debating.

[Smegma]

But black devil's point is still wrong.

[Espadon]

Correct. Now, I hope I've made my point, and this is all settled.

[Smegma]

The easiest way to explain it is just to say that the wheels only to decrease the friction forces from the OBLIGATORY contact to the land. (This was stated) However, stating in the same post that the plane's forces are applied by the engines would have also helped.

[The Geologist]

I was reading this whole fiasco part. Chroink is correct, due to the fact that there is a reasoning flaw here in Geologist's post.

First of all, we shall say that Boeing has invented a totally frictionless bearing for its 747's wheels. They have put it on a super treadmill that is moving at 300 mph westward. Held at the moment with a massive clamp, the 747 is lowered onto the treadmill, facing eastward. The aircraft is NOT moving, however, the wheels are spinning at the rate so that it would go at 300mph westward IF they were the wheels on a car (as you see, there are no engines hooked up to an aircraft's wheels). Now say, the pilot cranks the throttle up to 300 mph airspeed. The airplane will disregard the fact that the treadmill is moving 300mph WESTWARD and instead zoom off into the sky EASTWARD. This is because the aircraft's engines "bites into" the stationary air. Right before the aircraft takes off, the wheels would be moving at the equivalent of moving westward at 600 mph. Despite the fact that the treadmill is moving so fast, the air, at least at the engine's height, is stationary. Gases have low friction, being what they are. This is the same reason why we have air currents, because the atmosphere moves at different velocities at different latitudes (the principle is related to why figure skaters spin faster when they tuck everything in).

If this is still too confusing, then perhaps your time would be spent better on various other activities.

As taken fro the first post:

• Imagine an airplane standing on a gigantic treadmill. The plane is taking off, but the treadmill is moving in the opposite direction at the exact same speed. Would it still be able to lift off?

I bolded that part because it's very important.  The plane is taking off, as in it has it's engines already running at 300 m.p.h. airspeed (for the sake of using your example).  With the velocity the plane gets from the engines already going while the wheels spin away, it's still going the exact same speed as the treadmill.  Therefore it stays in place.  Because the plane stays in place, there is no air moving under the wing, and thus no lift.

What you're describing is a situation in which the plane is rolling on frictionless wheels, initially not taking off or moving with the help of its engines (which strays from the original question), and then using it's engines to achieve a greater velocity than the treadmill.  In that sort of situation the plane would take off eventually, but alas, that is not the situation described in the original question. 

[Smegma]

http://youtube.com/watch?v=-EopVDgSPAk

The wheels on the plane are not MEANT to move the plane, they are designed as such.

Technically, his phrasing would indicate only speed. So, we dont know it is accelerating, but we all assume he meant to say it was and so was the belt.

[Espadon]

I was reading this whole fiasco part. Chroink is correct, due to the fact that there is a reasoning flaw here in Geologist's post.

First of all, we shall say that Boeing has invented a totally frictionless bearing for its 747's wheels. They have put it on a super treadmill that is moving at 300 mph westward. Held at the moment with a massive clamp, the 747 is lowered onto the treadmill, facing eastward. The aircraft is NOT moving, however, the wheels are spinning at the rate so that it would go at 300mph westward IF they were the wheels on a car (as you see, there are no engines hooked up to an aircraft's wheels). Now say, the pilot cranks the throttle up to 300 mph airspeed. The airplane will disregard the fact that the treadmill is moving 300mph WESTWARD and instead zoom off into the sky EASTWARD. This is because the aircraft's engines "bites into" the stationary air. Right before the aircraft takes off, the wheels would be moving at the equivalent of moving westward at 600 mph. Despite the fact that the treadmill is moving so fast, the air, at least at the engine's height, is stationary. Gases have low friction, being what they are. This is the same reason why we have air currents, because the atmosphere moves at different velocities at different latitudes (the principle is related to why figure skaters spin faster when they tuck everything in).

If this is still too confusing, then perhaps your time would be spent better on various other activities.

As taken fro the first post:

• Imagine an airplane standing on a gigantic treadmill. The plane is taking off, but the treadmill is moving in the opposite direction at the exact same speed. Would it still be able to lift off?

I bolded that part because it's very important.  The plane is taking off, as in it has it's engines already running at 300 m.p.h. airspeed (for the sake of using your example).  With the velocity the plane gets from the engines already going while the wheels spin away, it's still going the exact same speed as the treadmill.  Therefore it stays in place.  Because the plane stays in place, there is no air moving under the wing, and thus no lift.

What you're describing is a situation in which the plane is rolling on frictionless wheels, initially not taking off or moving with the help of its engines (which strays from the original question), and then using it's engines to achieve a greater velocity than the treadmill.  In that sort of situation the plane would take off eventually, but alas, that is not the situation described in the original question. 

The aircraft is moving at 300mph. I'm talking airspeed. You're talking groundspeed. When an aircraft "takes off" it has to achieve the takeoff AIRSPEED. See the problem? With aircraft, you deal with airspeed. Cars, groundspeed. It's like apples to oranges.

[Smegma]

Another thing:

Airplanes are meant to be...in the air, unfortunately we don't keep them there all the time. THIS is why they have wheels, not to move via the contact force of friction. The force is generated by moving air, not by the contact force.

[LtKillroy]

http://youtube.com/watch?v=-EopVDgSPAk

The wheels on the plane are not MEANT to move the plane, they are designed as such.

Technically, his phrasing would indicate only speed. So, we dont know it is accelerating, but we all assume he meant to say it was and so was the belt.

Ok, now that WE HAVE A VIDEO wo don't really need to keep discussing this, do we. Lock.

[Smegma]

Hey, people might still wish to participate in a discussion.

[LtKillroy]

Why would we discuss whether or not something is possible when it has been proven it is possible. Makes no sense.

[blackdevil0742]

Here is a better explanation for this: http://www.straightdope.com/columns/060203.html and/ or http://www.straightdope.com/columns/060303.html

I was discussing an other thing as some noticed so don't mind my responses

[Graham]

http://youtube.com/watch?v=-EopVDgSPAk

The wheels on the plane are not MEANT to move the plane, they are designed as such.

Technically, his phrasing would indicate only speed. So, we dont know it is accelerating, but we all assume he meant to say it was and so was the belt.

He doesn't measure any kind of speed and you don't even see it lift because the kid is in the way. You can't use that as evidence either way.

[Espadon]

Oh come now, just think about it logically. The earth is pretty much a gigantic treadmill. It turns at 15'/min and I've never once heard of a plane that got caught up by that and stuck on the ground.

[Graham]

If you look at it that way we should have been thrown off a few minutes ago...

[Smegma]

http://youtube.com/watch?v=-EopVDgSPAk

The wheels on the plane are not MEANT to move the plane, they are designed as such.

Technically, his phrasing would indicate only speed. So, we dont know it is accelerating, but we all assume he meant to say it was and so was the belt.

He doesn't measure any kind of speed and you don't even see it lift because the kid is in the way. You can't use that as evidence either way.

I timed the results:

treadmill speed = speed 0 mph
total time to reach end ~ 1.50s seconds

treadmill speed =  4 mph
total time ~ 1.50s

treadmill speed = 10 mph
total time ~ 1.56s

If you don't believe me, go download a millisecond timer. Now, the final run he blocked the view so I tried to gage it by sound. That could account for the .06s (slight) difference in the time. But technically we would see a difference in the 4mph which we don't. This isn't a great way to proof, but he should have really timed the runs, but he didn't