*light blue touch paper*

[Sparta]

I couldn't be bothered reading through the thread so can someone just say whether or not there is a definitive agreed upon answer?

I'm gonna go with, no the plane wont fly because there's no lift under the wings.

 

[CyberPitz]

I agree with Sparta. It won't fly because the whole plane is still sitting in a stand still. You need the wind under the wings to life it for it to actually fly. If the plane isn't moving, then there is no wind..thus no lift.

 

[Steve]

wheels only reduce friction they don't remove it it.

the holding the skateboard in the air isn't comparable to an air plane on a run way, since the plane is actually on the ground and therefor experience friction. spin the wheels on the plane and the plane will move.

it's really not that ahrd to get.

wheels + gravity = friction

Right, but unlike in a car or on a human running, friction with the ground is not the way the plane generates motion. The plane generates motion by using its jets or prop or whatever to push against the air.

Yes, the wheels do create a little friction with the ground, and yes it will take the plane a little longer to take off because of it, but the force generated by the friction between the conveyor and the wheels is just too small when compared with the power of the jets pushing against the air to make that much of a difference.

 

[Asus]

For a plane to even begin to lift off it needs the propeller to pull it forward through the air. After it gets speed the air going over the wings will help lift it. We agree on that, right?

Lets see if I can explain it another way. Now when you swim, you are pulling yourself through the water without having to worry about friction of the ground right? While swimming, just think of your arms/legs as the propellers of the plane. The wheels negate the backwards pull of the belt so only the propellers are left and that is foward motion. So the plane will go forward from the propellers pulling the plane (but will take a lot longer than on flat ground) and the wings will eventually get enough air for lift.

I think where people are getting confused is that they think the belt will take away propeller's effect when really it just counters the wheels. The question assumes you know certain things though. Sorta vague since it does not explain that the belt takes away from the wheels only since that is where the friction is.

Nice flash btw.

 

[_Z_Ryuken]

You people are still discussing this? Good god...

 

[Yuri]

I agree with Sparta. It won't fly because the whole plane is still sitting in a stand still. You need the wind under the wings to life it for it to actually fly. If the plane isn't moving, then there is no wind..thus no lift.

Teehee, that's what I thought.

Until I realized that the wheels aren't what powers "jets"... that would be the "jets." So no matter how fast the wheels are spinning (a constant rate of twice as fast as usual), the plane is still going forward because of the forward force provided by the jets.

It's really quite a simple concept which just tricks people off the bat, cuz most people think of planes as being like cars-- powered by the wheels (at least on the ground). But once you get it... you get it. There needs be no discussion. It's completely simple.

 

[Naudian]

^ Yea..we already confirmed many pages back that the plane will take off!
Watch this Sparta, Cyber:
http://img450.imageshack.us/my.php?i...rplane22dg.swf
If you don't agree, go read the entire thread again...

And Prince, I think I see what you're saying, but the plane will still take off.
Wai?
Because the friction you keep talking about is not enough to over-power the engines. As you would have seen in short recoil's MSpaint work, the wheels only create a small amount of drag. NOT ENOUGH TO STOP THE PLANE.
I hope that's what you were getting at...so now you should understand:

-Yes the plane is heavy, and is indeed pushing the wheels against the conveyer belt with a lot of force, creating friction.
-And the conveyer belt moves at the same velocity of the *wheels. This creates even more friction (drag) but still, it's just not enough to overpower the engines that are pulling/pushing the plane...
You might say, "how do you know it's not enough to over-power the engines?" Well, it's instinctive really, I can't prove it as I'm no physics expert, but I'm pretty sure it's true.

*some people read the question wrong and assumed the conveyer belt matched the speed of the plane...but the question actually said it matches the speed of the wheels. Either way, the plane still takes off.

 

[Sparta]

That flash link didn't work.

So what, if i'm understanding this right, theoretically the conveyor doesnt have enough power to negate the planes propellers from generating airflow under the wings to allow flight?

This sounds like something Mythbusters can solve. Cause right now, all we have is theoretical evidence, but actual evidence is yet to be obtained. Plus if they ever can do this, i want them to blow up the plane.

 

[PriNcE oF SpAcE]

Right, but unlike in a car or on a human running, friction with the ground is not the way the plane generates motion. The plane generates motion by using its jets or prop or whatever to push against the air.

Yes, the wheels do create a little friction with the ground, and yes it will take the plane a little longer to take off because of it, but the force generated by the friction between the conveyor and the wheels is just too small when compared with the power of the jets pushing against the air to make that much of a difference.

now your asuming again that the engines generate more power than the conveyer belt. the question specifically states that conveyer belt will move at exact matching speed.

the fact that jets push against the air and not the ground doesn't really matter as long as the plane is still on the ground. the plane will only go faster than the conveyer belt and move when it has created enough lift to significantly reduce the friction of the wheels. that lift will not encure without air passing the wings.

 

[PriNcE oF SpAcE]

^ Yea..we already confirmed many pages back that the plane will take off!
Watch this Sparta, Cyber:
http://img450.imageshack.us/my.php?i...rplane22dg.swf
If you don't agree, go read the entire thread again...

And Prince, I think I see what you're saying, but the plane will still take off.
Wai?
Because the friction you keep talking about is not enough to over-power the engines. As you would have seen in short recoil's MSpaint work, the wheels only create a small amount of drag. NOT ENOUGH TO STOP THE PLANE.
I hope that's what you were getting at...so now you should understand:

-Yes the plane is heavy, and is indeed pushing the wheels against the conveyer belt with a lot of force, creating friction.
-And the conveyer belt moves at the same velocity of the *wheels. This creates even more friction (drag) but still, it's just not enough to overpower the engines that are pulling/pushing the plane...
You might say, "how do you know it's not enough to over-power the engines?" Well, it's instinctive really, I can't prove it as I'm no physics expert, but I'm pretty sure it's true.

*some people read the question wrong and assumed the conveyer belt matched the speed of the plane...but the question actually said it matches the speed of the wheels. Either way, the plane still takes off.

you're asuming the engines are more powerful than the conveyer belt...the question states this is not true.

the question doesn't mention the speed of the wheels so lets just stick with what the question says, and assume that conveyer belt moves at the same speed of the plane.

 

[Sulkdodds]

I've only read up to page 11 but now it makes actualy sense. Thank you for finally explaining clearly, you bastards.

 

[Parrot of doom]

you're asuming the engines are more powerful than the conveyer belt...the question states this is not true.

the question doesn't mention the speed of the wheels so lets just stick with what the question says, and assume that conveyer belt moves at the same speed of the plane.

You are completely wrong.

Friction has nothing to do with gravity. Nothing There is no relation between the frictional coefficient of a substance, and the gravitation pull of a body.


Its explained very simply. Tie a ruddy great balloon or helicopter to the aircraft, via a long rope and a pulley so that the lifting force of the balloon is translated into horizontal pull:

The ballon/helicopter is performing the exact same function as the engines of the aircraft. There is no difference. The conveyor does not understand this relationship; it simply moves at the same speed as the aircraft, but in the opposite direction. The freespinning wheels on the aircraft negate any effect that the conveyor has on the aircraft's forward speed.

If you cannot understand this premise, then you will never correctly answer the question. Thats not an insult, its a truth - there are questions/areas where I'm rubbish in life, but it doesn't mean I'm stupid.

Trust me, the plane will fly - and the speed of the conveyor has no effect beyond the ability of the wheels to spin at twice the rate they normally would.



/edit: PS I knew this thread would be controversial

 

[Unfocused]

I don't like analysing physics, but the conveyor belt "not knowing what the ****" simply rocks!

 

[Mutley]

I voted yes but didn't have a good reason why (my theory was really dumb, that it would just start hovering, lol ).

Now reading yours I'm abit confused, I agree but I'm no physics person to understand it. If the plane went 500mph, the belt would too, so the wheels wouldn't move? Confused.

 

[Beerdude26]

Look.
If you put a rocket engine on a skateboard.
And activate it.
It will start moving FORWARD because the wheels SPIN.
Like, ZOOMJ.

Second, you put the ZOOMJing skateboard on a conveyor belt.
The conveyor belt will move in the opposite direction.
The conveyor belt will move at the same speed of the skateboard.
The conveyor belt has an effect on THE WHEELS of the skateboard.
THE WHEELS start moving faster.
THE WHEELS will move at the speed the rocket engine PLUS the conveyor belt moves it.
The skateboard goes MORE ZOOMJ.
Like, ZOOMJ.
ZOOMJ
ZOOMJ
ZOOMJ
OH JESUS

 

[PriNcE oF SpAcE]

You are completely wrong.

Friction has nothing to do with gravity. Nothing There is no relation between the frictional coefficient of a substance, and the gravitation pull of a body.


Its explained very simply. Tie a ruddy great balloon or helicopter to the aircraft, via a long rope and a pulley so that the lifting force of the balloon is translated into horizontal pull:

The ballon/helicopter is performing the exact same function as the engines of the aircraft. There is no difference. The conveyor does not understand this relationship; it simply moves at the same speed as the aircraft, but in the opposite direction. The freespinning wheels on the aircraft negate any effect that the conveyor has on the aircraft's forward speed.

If you cannot understand this premise, then you will never correctly answer the question. Thats not an insult, its a truth - there are questions/areas where I'm rubbish in life, but it doesn't mean I'm stupid.

Trust me, the plane will fly - and the speed of the conveyor has no effect beyond the ability of the wheels to spin at twice the rate they normally would.



/edit: PS I knew this thread would be controversial

no I'm not wrong.

gravity does have an effect on friction! that's why heavier objects needs more force applied to them to move.

try crawling on your stomach with a sumo wrestler ontop...wondering why you move slower and have to use more energy to push yourself forward? because the weight of the sumo wrestler adds to the friction between you and the ground that's why.

add a couple of wheels under you and all it does it making it easier, it doesn't remove the friction only reduce it.

add some weights to your trolley and the more weight on the trolley the more friction and thus the bigger effect the conveyer belt will have. if you add more power to the conveyer belt than the balloon provides the trolley will move backwards and drag the balloon down, this wouldn't happen if there was no friction from the wheel or the wheels was truly free spinning. if the balloon and the conveyer belt power is equal the trolley would be at a stand still wheel spinning, not moving forward.

if the trolley was moving forward it would mean:

a) baloon is moving faster than conveyer belt.

b) the baloon has enough power to negate friction/gravity on it's own. in which case it would be a rocket or similar device, not a normal airplane.

 

[Beerdude26]

Well, you have a point there (more weight = more friction), but if your theory was the case, how in the bloody hell do you explain airplanes going up in the air going ZOOMJ ?

 

[Mutley]

Look.
If you put a rocket engine on a skateboard.
And activate it.
It will start moving FORWARD because the wheels SPIN.
Like, ZOOMJ.

Second, you put the ZOOMJing skateboard on a conveyor belt.
The conveyor belt will move in the opposite direction.
The conveyor belt will move at the same speed of the skateboard.
The conveyor belt has an effect on THE WHEELS of the skateboard.
THE WHEELS start moving faster.
THE WHEELS will move at the speed the rocket engine PLUS the conveyor belt moves it.
The skateboard goes MORE ZOOMJ.
Like, ZOOMJ.

I don't get it!

The wheels will still go the same speed as it is going forwards backwards. I'm no physics person.

 

[PriNcE oF SpAcE]

Well, you have a point there (more weight = more friction), but if your theory was the case, how in the bloody hell do you explain airplanes going up in the air going ZOOMJ ?

because normally the run way isn't moving in the opposite direction but is fixed in place.

so the plane has enought engine power to move it on a horizontal plane, but will only be able to move on the vertical plane with the aid of air passing the wings.

that's why you have run ways and wings...to make air pass the wings and help with lift off.

we're assuming the question is based on an normal aircraft. normal aircrafts aren't able to lift of the ground using just the air they push with their engines.

one unlikely scenario however will have the plane and the conveyer belt moving at speeds that would make the plane skit across it, like rock skitting over water(the friction will cause an upward push) making the plane catch air time, since the plane can push air it might be able to move forward slightly, but I doubt fast enough as to gain any real lift, so it will head back down again, and you gotta wonder if the gained speed of the conveyer belt(to match that of the plane) wouldn't be able to toss the plane back a bit, essentially making the plane do stand still skits. it's also worth mentioning that with rock skitting you've already applied a force that would be able to free the rock of friction and gravity enough for it to essentially be a rocket-like device.(you can simply toss it thru the air) so I think for the friction to cause an upward push, the airplane would hvae to be classified as a rocket anyways(which we assume it is not).

 

[Maxi]

We Need An Experiment!

 

[PriNcE oF SpAcE]

good luck finding a plane and a conveyer belt big enough to support it.(and be able to match the speed of a plane)

 

[Mutley]

R/C Planes & Tesco till conveyors ftw!

 

[MuToiD_MaN]

Imagine this:
Instead of a plane, have a jet sled WITHOUT wings, just the jet engines from the plane and wheels. No lift will ever be generated, no magic cables suspending it, etc.

* Sled on conveyor belt, moving at 200 MPH
* Sled's wheels spin at, let's say 200 RPM

--Conveyor belt reacts to this and speeds up instantly to 200 MPH--

Result:
* Sled moving on conveyor belt at 195 MPH -- okay let's be generous -- 190 MPH -- relative to real ground
* Wheels now spinning at almost 400 RPM

If the conveyor belt is moving at the same speed as the sled, it will not stop foreward movement. Even if it was matching it all the way through its acceleration.

 

[Parrot of doom]

no I'm not wrong.

gravity does have an effect on friction! that's why heavier objects needs more force applied to them to move.

try crawling on your stomach with a sumo wrestler ontop...wondering why you move slower and have to use more energy to push yourself forward? because the weight of the sumo wrestler adds to the friction between you and the ground that's why.

add a couple of wheels under you and all it does it making it easier, it doesn't remove the friction only reduce it.

add some weights to your trolley and the more weight on the trolley the more friction and thus the bigger effect the conveyer belt will have. if you add more power to the conveyer belt than the balloon provides the trolley will move backwards and drag the balloon down, this wouldn't happen if there was no friction from the wheel or the wheels was truly free spinning. if the balloon and the conveyer belt power is equal the trolley would be at a stand still wheel spinning, not moving forward.

if the trolley was moving forward it would mean:

a) baloon is moving faster than conveyer belt.

b) the baloon has enough power to negate friction/gravity on it's own. in which case it would be a rocket or similar device, not a normal airplane.

Gravity has no effect on friction. None. You are completely and utterly wrong.

If I take a piece of rubber and move it against another piece of wood, there will be a certain amount of force required for the piece I'm holding to move. Placing a weight on that object only increases its inertia - it does not increase the frictional properties of the piece of rubber. More force is required to move it due to the combined effect of inertia and the gravitational attraction pulling on another axis, but this is nothing to do with friction. So stop now.

Your grasp of physics is I'm afraid very sadly lacking. I struggled with this question when I first heard it, but after having the obvious pointed out to me (as most people here have read, in the thread) I understood the problem. You haven't.



Just stop and think. THINK:

The belt is at 0mph. The plane is at 0mph

The plane throttles to 10mph. The belt moves at 10mph in the other direction.

The plane is moving at 10mph relative to the atmosphere and the land surrounding the belt

The plane is moving at 20mph relative to the belt

The wheels are spinning to accomodate the difference in speed between the plane, and the belt - 20mph



What is so hard to grasp about this concept? The wheels do not propel the aircraft. No aircraft in the world are propelled by wheels

If you cannot understand these simple facts, then you never will. You are wrong. Completely, utterly, inescapably, 100% wrong.

 

[Parrot of doom]

we're assuming the question is based on an normal aircraft. normal aircrafts aren't able to lift of the ground using just the air they push with their engines.

All aircraft, every single powered aircraft in the entire world lifts off the ground using the air they push with their engines!

Are you suggesting they take off strapped to the backs of little motor cars? Or invisible dwarves who run in front of them, pulling the aircraft along with invisible ropes?

 

[Shamrock]

All aircraft, every single powered aircraft in the entire world lifts off the ground using the air they push with their engines!

Are you suggesting they take off strapped to the backs of little motor cars? Or invisible dwarves who run in front of them, pulling the aircraft along with invisible ropes?

I hate you, too.

 

[MuToiD_MaN]

Gravity has no effect on friction. None. You are completely and utterly wrong.

If I take a piece of rubber and move it against another piece of wood, there will be a certain amount of force required for the piece I'm holding to move. Placing a weight on that object only increases its inertia - it does not increase the frictional properties of the piece of rubber. More force is required to move it due to the combined effect of inertia and the gravitational attraction pulling on another axis, but this is nothing to do with friction. So stop now.

YOU, my friend, are completely and utterly wrong, in terms of your description of the rubber and wood:

Static friction: (static friction constant) * Normal Force.
Kinetic friction: (kinetic friction constant) * Normal Force.
where the Normal Force is the force the surface is acting on the object. EX: A box sitting on a flat surface has a normal force EQUAL and OPPOSITE to the force of the weight of the object (hint: that's where gravity fits in)
Placing a weight on an object DEFINITELY increases the friction because that adds to normal force.

Inertia is there too, sure. But so is increased friction. If you've taken physics, apparently you need to retake it.

Nota bene: in our situation, this would be factored if the plane had no wheels.

 

[MuToiD_MaN]

All aircraft, every single powered aircraft in the entire world lifts off the ground using the air they push with their engines!

Are you suggesting they take off strapped to the backs of little motor cars? Or invisible dwarves who run in front of them, pulling the aircraft along with invisible ropes?

Wrong again. All aircraft MOVE FORWARD with the air they push with their engines. They lift off because of the forces caused by the air they are moving through ONCE THEY ARE MOVING FORWARD. Get it straight.

You guys can finish your argument, I'm playing my "Screw this I'm out of here" forum card.

 

[Parrot of doom]

Anyway, all this is irrelevant. Right now, the plane in question is landing on the other side of the world, and the pilot is reading this thread and laughing.

 

[Reaktor4]

57 of you are stupid.

 

[K e r b e r o s]

I voted yes, which it would.

It has no lift. Gawd, some people are idiots.

 

[PriNcE oF SpAcE]

All aircraft, every single powered aircraft in the entire world lifts off the ground using the air they push with their engines!

Are you suggesting they take off strapped to the backs of little motor cars? Or invisible dwarves who run in front of them, pulling the aircraft along with invisible ropes?

read what I said retard.

no normal aircraft is lifting off the ground by use of the air their engines push alone! it's a combination of engine thrust + lift generated by the air passing the wings! otherwise they're classified as rockets or special fighter jets(e.g. Harrier jet)

 

[Steve]

now your asuming again that the engines generate more power than the conveyer belt. the question specifically states that conveyer belt will move at exact matching speed.

And YOU'RE still assuming that the plane is dependent on the wheels for forward movement. This isn't a CAR. The plane doesn't move forward because the wheels are spinning, the wheels spin because the plane is moving forward. All the wheels do is lubricate the plane's movement along the ground.

 

[PriNcE oF SpAcE]

YOU, my friend, are completely and utterly wrong, in terms of your description of the rubber and wood:

Static friction: (static friction constant) * Normal Force.
Kinetic friction: (kinetic friction constant) * Normal Force.
where the Normal Force is the force the surface is acting on the object. EX: A box sitting on a flat surface has a normal force EQUAL and OPPOSITE to the force of the weight of the object (hint: that's where gravity fits in)
Placing a weight on an object DEFINITELY increases the friction because that adds to normal force.

Inertia is there too, sure. But so is increased friction. If you've taken physics, apparently you need to retake it.

Nota bene: in our situation, this would be factored if the plane had no wheels.

thank you.

nota bene(whatever that means): this should also be factored in even if the plane got wheels. like I've said plenty of times already, the wheels don't magically remove all the friction, they only reduce the friction. add enough wait ontop of a set of wheels and you will eventually have weighted them down to the point where they wouldn't turn or move unless you apply tremendous force. otherwise there wouldn't be use for tow-trucks and the like since ZOMG omg anyone would be able to move any kind of object as long as it has wheels.

 

[PriNcE oF SpAcE]

An YOU'RE still assuming that the plane is dependent on the wheels for forward movement. This isn't a CAR. The plane doesn't move forward because the wheels are spinning, the wheels spin because the plane is moving forward. All the wheels do is lubricate the plane's movement along the ground.

no I am not. I've never said the plane relied on the movement of the wheels to move.

I'm saying that as long as the plane is on the ground it will be effected by the movement of the wheels and/or ground.

 

[Reaktor4]

I dont think hes ever going to get it.

 

[Steve]

no I am not. I've never said the plane relied on the movement of the wheels to move.

Well, then you should understand that because the wheels aren't how the plane generates movement, how fast they spin in whatever direction doesn't significantly affect the plane's movement.

Okay, replace the plane with a human.

Replace the wheels with rollerblades.

Replace the jet engines with a rope attached to a wall.

The human pulls the rope to go forward. The wheels of the skates are spinning with the conveyor belt, but it doesn't matter because the rope is independent of the movement of the conveyor belt, so the person is free to advance along the conveyor belt by pulling the rope.

 

[The Monkey]

It won't take off. Get over it.

 

[PriNcE oF SpAcE]

1) Just stop and think. THINK:

2) The belt is at 0mph. The plane is at 0mph

3) The plane throttles to 10mph. The belt moves at 10mph in the other direction.

4)The plane is moving at 10mph relative to the atmosphere and the land surrounding the belt

5)The plane is moving at 20mph relative to the belt

6) The wheels are spinning to accomodate the difference in speed between the plane, and the belt - 20mph



7) What is so hard to grasp about this concept? The wheels do not propel the aircraft. No aircraft in the world are propelled by wheels

8) If you cannot understand these simple facts, then you never will. You are wrong. Completely, utterly, inescapably, 100% wrong.

1) ok I will...

2) right gotcha none of the is moving.

3)right gotcha, the plane isn't moving forward.

4) no. the plane is standing still, the thrust it gained was cancelled by the the belt's movement. as long as the plane is on the ground and has no means to lift or cancel out the friction, the plane will be effected by the movement of the belt. only thing moving at 10mph(approx) would be the air shot out from behind.

5)how so? it seems that you're comparing the speed of the passing ground(the conveyer belt in this case) and what normal forward movement that would translate into, and not the actual movement of the plane. yes the relative speed between the plane and the belt would be 20mph in opposite directions but the belt is actively moving at 10 mph in the one direction and the plane 10mph in the other, so they'd cancel out eachother in terms of actualy forward movement of the plane.

6) yes the wheel spin, but nothing is moving along the horizontal plane.

7) I've never said the the wheels propel the aircraft foward. but as long as the wheels are on the ground with no means to lift them off. if the ground is moving the wheels would move and the areplane would aswell.

8) prove it.

 

[Dumb Dude]

The human pulls the rope to go forward. The wheels of the skates are spinning with the conveyor belt, but it doesn't matter because the rope is independent of the movement of the conveyor belt, so the person is free to advance along the conveyor belt by pulling the rope.

This is as simple as its going to get. If the Prince still doesn't think it can take off, then he is clearly an idiot.