Will the plane takeoff?

[PARAGON]

Originally Posted by Wisha Haddan H3

Don't have a heart attack, paragon. The questions are worded slightly differently, but the scenarios are exactly the same. Only the scale is different, which isn't relevant as long as we're talking about models that can actually fly. The physics of flight are the same regardless of size/scale/mass.

Go eat some dinner. I think maybe your blood sugar is off.

No, not stupid for you too.

Speed is relative. Figure that the fvck out and you will see why the questions are totally different.

[Wisha Haddan H3]

Originally Posted by PARAGON

There are 2 answers to this question.

Let's hear it

[PARAGON]

Originally Posted by Wisha Haddan H3

Let's hear it

Simple

Yes

and

No

[PARAGON]

Originally Posted by Wisha Haddan H3

Don't have a heart attack, paragon. The questions are worded slightly differently, but the scenarios are exactly the same. Only the scale is different, which isn't relevant as long as we're talking about models that can actually fly. The physics of flight are the same regardless of size/scale/mass.

Go eat some dinner. I think maybe your blood sugar is off.

So our two resident lieberal einsteins don't quite understand comprehension. I'll 'splain it.

The questions posed in the links provided by the pretzel pusher say "the speed of the wheels"

The question posed here says "the plane's speed" Now, I might only have an IQ of 180+ but those are not the same.

[H2Finally]

Is this similar to tying the tail off a (model) airplane and gunning the engine and see if the plane will lift vertically off without any forward horizontal movement?

If under normal conditions a plane's engine must work with or against prevailing wind to create enough trust for lift, then presumably you can get one with big enough jets or propellers that will be able to create enough backwash of airstream to lift the plane without the plane actually moving forward.

So if the engine is big enough and/or in the right place relative to creating the airstream against the wings, maybe?

Now, wheather or not the plane can control yaw and pitch the moment it's airborne, without "normal" airstream, I'm not certain..

[Wisha Haddan H3]

Originally Posted by PARAGON

That really has nothing to do with it.

Wheels have to turn in either situation. In the case of the plane, it has to move relative to air to lift off, a car doesn't. That is the only difference. How they apply their power has no bearing on this riddle.

Even if a plane is "pushing the air" it has to push against that air (thrust) to make the plane move, gaining speed. As it gains that speed the conveyor is matching the speed in the opposite direction, same as a car would.

Somehow missed this post. On the contrary, how airplanes apply their power is central to this riddle.

For example, when we walk or run, our propulsion is based on applying force to the ground. We push backwards and resistance sends us forward relative to the ground and air. On a treadmill, our feet push the conveyor belt and all our walking force is spent keeping up with it. We feel no wind in our face because our speed (relative to the ground and air) is zero. A car, bicycle or any vehicle that uses ground propulsion would experience the same effects on a conveyor belt.

However, an airplane's engines don't push the ground. They apply force directly to the air. When the air pushes back, the plane is thrust forward through the atmosphere at ground level. The wing's movement through the surrounding static air creates lift and the plane takes off.

On a conveyor belt runway, the exact same process occurs ... the engines push air backwards and the plane is thrust forward through the atmosphere. The conveyor belt can spin all it wants to, but it will only make the wheels spin faster. It can't hold the plane back because it isn't attached to the plane. Since the plane thrusts directly on the air, it doesn't rely on the conveyor belt for propulsion the way a person or car would. Instead, it slices through the air and takes off when enough lift is achieved.

[SnakeH2]

Originally Posted by H2 rocks me

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but
in the opposite direction) instantly.

Will the plane be able to take off?

Yes

[Wisha Haddan H3]

Originally Posted by PARAGON

Simple

Yes

and

No

Thanks for clearing that up

[h2co-pilot]

Okay, just stop.

EVERYONE JUST STOP!

[PARAGON]

Originally Posted by Wisha Haddan H3

Somehow missed this post. On the contrary, how airplanes apply their power is central to this riddle.

For example, when we walk or run, our propulsion is based on applying force to the ground. We push backwards and resistance sends us forward relative to the ground and air. On a treadmill, our feet push the conveyor belt and all our walking force is spent keeping up with it. We feel no wind in our face because our speed (relative to the ground and air) is zero. A car, bicycle or any vehicle that uses ground propulsion would experience the same effects on a conveyor belt.

However, an airplane's engines don't push the ground. They apply force directly to the air. When the air pushes back, the plane is thrust forward through the atmosphere at ground level. The wing's movement through the surrounding static air creates lift and the plane takes off.

On a conveyor belt runway, the exact same process occurs ... the engines push air backwards and the plane is thrust forward through the atmosphere. The conveyor belt can spin all it wants to, but it will only make the wheels spin faster. It can't hold the plane back because it isn't attached to the plane. Since the plane thrusts directly on the air, it doesn't rely on the conveyor belt for propulsion the way a person or car would. Instead, it slices through the air and takes off when enough lift is achieved.

Not entirely true.

The plane has to gain distance over time. If the conveyor moves the plane rearward for every instance in time the plane's thrust attempts to move it forward, the net movement relative to the air would amount to zero.

[PARAGON]

Originally Posted by Wisha Haddan H3

Thanks for clearing that up

I can argue this either way due to the manner in which the question was asked. Hence the reason for the yes, no answers.

The question actually needs more clarification or one has to make some assumptions to answer it without saying a definitive yes due to VTOL aircraft.

With that, I will be going and reading the big book of questions with my daughter.

[H2Finally]

A simple yes is wrong. Otherwise, airports will do away with long runways, and helicopters will be obsolete.

We need H2 GTS to chime in here...

[deserth3]

Speed of a planes wheels during take off is irelevent (other than the tire will blow if it rotates too fast) to the plane.
Relative wind speed across the wing is what's important for the wing to provide lift.
Thus a plane with a take off speed of 60 knots is capable of taking off in a 60 knot headwind and not move with relation to the earth. This is why small planes are tied down when parked.

[PARAGON]

I predict Ken will ask something about a fly

[Wisha Haddan H3]

Originally Posted by PARAGON

That's not true. Newton's law of motion states that the rocket or plane wants to stay still. As power is applied, as soon as it wants to start to roll, the conveyor moves, sending the motion back to a zero point.

That's where the conundrum lies with this version of the question. The plane can really never get up to any speed because it can't get past zero simply due to the limitations of the question IF you make certain assumptions OR it will take off IF you make other assumptions.

If the speed of the plane will always be instantaneously matched, the forward movement of the plane will never increase relative to it's surroundings.

If the plane starts to move at x MPH and instaneously the belt moves it -X MPH, the body of the plane remains still and actually does not move from a math standpoint.

But, assuming it's not a fictional question and the plane can move past this fictional "barrier of movement" then, as the plane increases it's speed, the plane is moving through the air and the belt is moving beneath and theoretically moving the wheels twice as fast.

That's why there were apparently different versions of the question. The one here was too vague and allowed for the No answer to be argued. The ones Bluehummer posted, that said speed relative to the wheels, changes the whole argument and allows the "body" of the plane to move without respect to the wheels.

Thank you for the coherent explanation. The only flaw in your evaluation lies in your application of the 3rd law of motion. "For every action there is an equal and opposite reaction".

A car on the conveyor would behave exactly as you describe, since its forward motion is dependent on the force its wheels apply to the conveyor surface. The wheels turn, exerting rearward force on the conveyor belt. The conveyor rolls, absorbing the force and negating forward motion relative to the ground next to the conveyor and the air around it. In other words, although the car moves forward relative to the conveyor, it remains stationary relative to the ground and air.

However, an airplane doesn't have drive wheels. Its forward motion depends the force of the props applied directly to the air. The props turn, exerting force on the air. As air is pushed rearward, the props are pushed in the opposite direction and the plane moves forward through the air, rolling over the conveyor's surface. Meanwhile the conveyor tries to spin, as if to counteract the forward motion of the plane, but the plane's wheels roll freely over it at higher and higher speeds. As the props push air rearward, the wings slice through the static air around the plane until the airflow over the wings produces enough lift for takeoff.

Nothing can stop the plane from taking off unless the tires blow out. Then, the extra friction between the landing gear and the conveyor could crash the plane or slow it down enough to prevent takeoff velocity.

[PARAGON]

Originally Posted by Wisha Haddan H3

Thank you for the coherent explanation. The only flaw in your evaluation lies in your application of the 3rd law of motion. "For every action there is an equal and opposite reaction".

A car on the conveyor would behave exactly as you describe, since its forward motion is dependent on the force its wheels apply to the conveyor surface. The wheels turn, exerting rearward force on the conveyor belt. The conveyor rolls, absorbing the force and negating forward motion relative to the ground next to the conveyor and the air around it. In other words, although the car moves forward relative to the conveyor, it remains stationary relative to the ground and air.

However, an airplane doesn't have drive wheels. Its forward motion depends the force of the props applied directly to the air. The props turn, exerting force on the air. As air is pushed rearward, the props are pushed in the opposite direction and the plane moves forward through the air, rolling over the conveyor's surface. Meanwhile the conveyor tries to spin, as if to counteract the forward motion of the plane, but the plane's wheels roll freely over it at higher and higher speeds. As the props push air rearward, the wings slice through the static air around the plane until the airflow over the wings produces enough lift for takeoff.

Nothing can stop the plane from taking off unless the tires blow out. Then, the extra friction between the landing gear and the conveyor could crash the plane or slow it down enough to prevent takeoff velocity.

You simply don't get it. It has nothing to do with it.

The question itself is self-limiting. Regardless of tires, planes, trains or automobiles. The moment it states that the conveyor will match speed with the airplane, period, it is stating that the plane will never move relative to the air. It will never gain speed.

Has nothing to do with physics. It's logic being applied to the question. THAT'S THE REASON FOR THE YES/NO ANSWER.

The question is in itself flawed.

The crap you are reading on some physics site is accurate if you pose the question where the speed is relative to the planes wheels or relative to anything. But since it is left wide open, an assumption would have to be made to suggest that the plane ever moves.

The reason is because due to the limits of the question, it's suggesting that the plane never breaks from zero speed.

It doesn't matter what type of propulsion is used. Whether its magnetic, some big hand, jet, prop, plasmic or whatever. The plane can never move simply because the equation offered by the question says it can't.

[KenP]

This is from a pilot relative in his early 50's that has been flying since he was 15. He's flown and had license to fly pretty much every type of aircraft. He was even a 'copter pilot in one of the Rambo movies. He currently flies for Southwest.

Ahhh, the old moving conveyor belt trick!!! The airplane will NOT takeoff. It has no airspeed with which to generate lift. Look at it this way. If the thrust of the engines were to generate 100 mph of forward movement but the conveyor belt cancelled the movement by moving the same speed in the opposite direction, you could stand to the side of the belt and hold onto the wing of the airplane cause it isn't moving relative to the ground. Now, since it isn't moving relative to the ground, and no mention was made of a wind blowing, the airspeed would be zero. No airspeed, no lift, no fly!. On the other hand, you could attach a cable to the nosegear so the airplane can't move across the ground and then blow a 100 mph wind over the wing from a giant fan, and the airplane would sense an airspeed of 100 mph and it would indeed fly, just like the Wright brothers did in the strong winds at Kitty Hawk with their tethered airplanes.

[Wisha Haddan H3]

Originally Posted by PARAGON

You simply don't get it. It has nothing to do with it.

The question itself is self-limiting. Regardless of tires, planes, trains or automobiles. The moment it states that the conveyor will match speed with the airplane, period, it is stating that the plane will never move relative to the air. It will never gain speed.

Has nothing to do with physics. It's logic being applied to the question. THAT'S THE REASON FOR THE YES/NO ANSWER.

The question is in itself flawed.

The crap you are reading on some physics site is accurate if you pose the question where the speed is relative to the planes wheels or relative to anything. But since it is left wide open, an assumption would have to be made to suggest that the plane ever moves.

The reason is because due to the limits of the question, it's suggesting that the plane never breaks from zero speed.

It doesn't matter what type of propulsion is used. Whether its magnetic, some big hand, jet, prop, plasmic or whatever. The plane can never move simply because the equation offered by the question says it can't.

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction) instantly.

Will the plane be able to take off?

The question is not flawed. It also never states the plane never breaks from zero speed. It is clear, direct and perfectly logical. Here's why. The conveyor can match the plane's forward velocity in the opposite direction because it is not connected to the airplane in any way, neither by physical attachments nor by forces. Since the airplane rolls on wheels, it can move forward at 100 knots while the conveyor moves backward at 100 knots. The relative speed between the two is 200 knots, and there is no contradiction in either logic or physics. Or the conveyor can move forward with the plane so the relative speed between them is 0 knots. Either way, the plane is moving at 100 knots relative to the air it is pushing through.

There is a logical flaw but it lies in your assumption that the relative speed between the plane and the conveyor determines the relative speed between the plane and the static air around it.

A ground-based conveyor cannot hold back a freewheeling vehicle that uses air for its locomotion. If the scenario involved an airplane in a wind tunnel, a submarine in a water current, a car on a conveyor or any vehicle where the medium of propulsion could be reversed, you would be absolutely correct. But that's not the case here.

The conveyor is a ground-based reversal, but the air around the airplane hasn't been touched. It remains static and the props can pull the airplane through it, causing airflow, lift and takeoff. This is the correct solution to the riddle.
______________

To me what makes this question interesting isn't just the physics. It's our human approach to the problem. Human experience is ground-based. We see birds and airplanes fly, but we cannot. Whether we walk, drive, skate or bicycle, we depend on forces pushing against the ground for locomotion. So our instinctive approach to this problem is also ground-based.

When we imagine ourselves on a conveyor, we realize that unless we walk on it, it will carry us along. We also realize that if the conveyor matches our walking speed, our position relative to the ground and air next to us will remain the same.

Our experience tells us that if we put an airplane on the conveyor, it will also be carried along, and if it tries to move forward it will also remain in the same place relative to the ground and air next to it. We also know that lift requires airflow, and if the plane's position is stationary relative to the air, there can be no lift and it cannot take off.

We assume all this from our ground-based experience ... but the reality is counter-intuitive.

First, there's the question of friction on the conveyor. When we stand on a treadmill, our feet stick to it through friction and we are pulled along unless we walk. However, the airplane is mounted on wheels that roll freely on it. It does not stick to the conveyor and is not pulled backwards as we would be. Thus, the conveyor cannot hold the airplane back.

Second, there's the question of propulsion. When we walk on a conveyor, our movement results from pushing against the moving conveyor with our feet. However, an airplane doesn't drive on the conveyor using its wheels ... the wheels roll freely over the conveyor, as the props push against the static air above it. Newton's 3rd law allows the plane to move forward, independently of the ground-based conveyor. The wing is drawn through the static air around it and the resulting airflow creates lift, allowing the plane to take off.

Thus, the speed and direction of the conveyor below the plane is irrelevant unless the tires blow.

[PARAGON]

Originally Posted by Wisha Haddan H3

A plane is standing on a runway that can move (like a giant conveyor
belt). This conveyor has a control system that tracks the plane's
speed and tunes the speed of the conveyor to be exactly the same (but in the opposite direction) instantly.

Will the plane be able to take off?

The question is not flawed. It also never states the plane never breaks from zero speed. It is clear, direct and perfectly logical. Here's why. The conveyor can match the plane's forward velocity in the opposite direction because it is not connected to the airplane in any way, neither by physical attachments nor by forces. Since the airplane rolls on wheels, it can move forward at 100 knots while the conveyor moves backward at 100 knots. The relative speed between the two is 200 knots, and there is no contradiction in either logic or physics. Or the conveyor can move forward with the plane so the relative speed between them is 0 knots. Either way, the plane is moving at 100 knots relative to the air it is pushing through.

There is a logical flaw but it lies in your assumption that the relative speed between the plane and the conveyor determines the relative speed between the plane and the static air around it.

A ground-based conveyor cannot hold back a freewheeling vehicle that uses air for its locomotion. If the scenario involved an airplane in a wind tunnel, a submarine in a water current, a car on a conveyor or any vehicle where the medium of propulsion could be reversed, you would be absolutely correct. But that's not the case here.

The conveyor is a ground-based reversal, but the air around the airplane hasn't been touched. It remains static and the props can pull the airplane through it, causing airflow, lift and takeoff. This is the correct solution to the riddle.
______________

To me what makes this question interesting isn't just the physics. It's our human approach to the problem. Human experience is ground-based. We see birds and airplanes fly, but we cannot. Whether we walk, drive, skate or bicycle, we depend on forces pushing against the ground for locomotion. So our instinctive approach to this problem is also ground-based.

When we imagine ourselves on a conveyor, we realize that unless we walk on it, it will carry us along. We also realize that if the conveyor matches our walking speed, our position relative to the ground and air next to us will remain the same.

Our experience tells us that if we put an airplane on the conveyor, it will also be carried along, and if it tries to move forward it will also remain in the same place relative to the ground and air next to it. We also know that lift requires airflow, and if the plane's position is stationary relative to the air, there can be no lift and it cannot take off.

We assume all this from our ground-based experience ... but the reality is counter-intuitive.

First, there's the question of friction on the conveyor. When we stand on a treadmill, our feet stick to it through friction and we are pulled along unless we walk. However, the airplane is mounted on wheels that roll freely on it. It does not stick to the conveyor and is not pulled backwards as we would be. Thus, the conveyor cannot hold the airplane back.

Second, there's the question of propulsion. When we walk on a conveyor, our movement results from pushing against the moving conveyor with our feet. However, an airplane doesn't drive on the conveyor using its wheels ... the wheels roll freely over the conveyor, as the props push against the static air above it. Newton's 3rd law allows the plane to move forward, independently of the ground-based conveyor. The wing is drawn through the static air around it and the resulting airflow creates lift, allowing the plane to take off.

Thus, the speed and direction of the conveyor below the plane is irrelevant unless the tires blow.

The logic simply eludes you.

You are making an assumption to come to your conclusion. An assumption that is not offered by the question.

tracks the plane's speed

plane's speed relative to what? Relative to the conveyor? Airspeed, relative to the surrounding air?

If it's airspeed, the very point at which the plane breaks the hold and theoretically begins to move, the conveyor would be moving it backwards and the wheels would never rotate and the plane would remain stationary. The plane is not being held stationary by any physical force, it's being held by the question. You have to assume that the plane starts to move and rotate the tires for the plane to gain airspeed. Well the question limits this assumption because one can make an assumption that allows for a different answer, therefore the question is flawed in that it allows for a yes and an no answer.

If you can't see the simplicity of logic. I can't help further.

You have to go and make it "fit" into

[NEOCON1]

i want to see paragon hit the dash