Will the plane takeoff?

[dеiтайожни]

Yes.

[KenP]

No. The plane is "standing".

Or:

No. The plane isn't moving.

[PARAGON]

Originally Posted by KenP

No. The plane is "standing".

Or:

No. The plane isn't moving.

be able to

[BlueTJCO]

it would take off. just think physics, F=m*a. The forward force (from the thrust) in both case is always bigger than the backward force (due to the friction of the wheel and ground, and it's very small compare to the thrust force), therefore the net force is always forward. So the plane will accelerate forward in both cases and take off.


Next Please

[KenP]

Originally Posted by KenP

No. The plane is "standing".

Or:

No. The plane isn't moving.

You're stupid. It will take off.

All the conveyor will do is cause the wheels to spin wildly. Imagine a rocket on wheels on the same conveyor. That rocket is going to take off...with the wheels spinning off.

What the wheels and conveyor do is irrelavent as none of that provides any propulsion. The wheels lower friction and provide for braking.

Theoretically, the conveyor could be moving backwards at double the speed of the plane and it still wouldn't matter. That would only cause the wheels to spin even faster, but the plane will still be getting thrust, moving forward and generating lift.

[SnakeH2]

Originally Posted by KenP

You're stupid. It will take off.

Best arguement yet!!!

[PARAGON]

Originally Posted by KenP

You're stupid. It will take off.

All the conveyor will do is cause the wheels to spin wildly. Imagine a rocket on wheels on the same conveyor. That rocket is going to take off...with the wheels spinning off.

What the wheels and conveyor do is irrelavent as none of that provides any propulsion. The wheels lower friction and provide for braking.

Theoretically, the conveyor could be moving backwards at double the speed of the plane and it still wouldn't matter. That would only cause the wheels to spin even faster, but the plane will still be getting thrust, moving forward and generating lift.

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.

[KenP]

I didn't look at his links () so I can't speak for that.

I do know that if I take a bottle rocket and attach it to a Matchbox on a beltsander spinning at full speed, light the rocket, it's going to go. Unless I accidentally sand my fingertips off.

I got my answer by cheating and reading a physics site. No, I didn't read all 15 pages!!!! Just the first and last few.

BTW, when I'm driving down the road and a fly is in the car, why doesn't the fly it the dash when I hit the brakes. And if the fly is flying around from front to back while I'm driving 55, what's the fly's speed in each direction?

[PARAGON]

Originally Posted by KenP

I didn't look at his links () so I can't speak for that.

I do know that if I take a bottle rocket and attach it to a Matchbox on a beltsander spinning at full speed, light the rocket, it's going to go. Unless I accidentally sand my fingertips off.

I got my answer by cheating and reading a physics site. No, I didn't read all 15 pages!!!! Just the first and last few.

BTW, when I'm driving down the road and a fly is in the car, why doesn't the fly it the dash when I hit the brakes. And if the fly is flying around from front to back while I'm driving 55, what's the fly's speed in each direction?

speed relative to what?

he's basically hovering in the car since the air in the car is "not moving"

the mass of the air and his mass is so small that he can accomodate the change in speed of the car because the "air" he's hovering in doesn't all go rushing to front.

Say, like if the car's interior was 1/4 full of water. All the water would rush to the front and a fish that was hovering in the water would go with it.

[KenP]

Would he smack the dash? I want to see something hit the dash.

[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.

[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.

[DURAMAX TIM]

Originally Posted by KenP

You're stupid. It will take off.

All the conveyor will do is cause the wheels to spin wildly. Imagine a rocket on wheels on the same conveyor. That rocket is going to take off...with the wheels spinning off.

What the wheels and conveyor do is irrelavent as none of that provides any propulsion. The wheels lower friction and provide for braking.

Theoretically, the conveyor could be moving backwards at double the speed of the plane and it still wouldn't matter. That would only cause the wheels to spin even faster, but the plane will still be getting thrust, moving forward and generating lift.

same as a float plane or plane w/ skis, wheels don't have to roll to take off.

[PARAGON]

Depends on the plane.

The tires might blow due to the speed.

[BlueTJCO]

Originally Posted by PARAGON

Depends on the plane.

The tires might blow due to the speed.

Thats the correct answer. At 500mph the tires would blow for sure... Aircrafts average take off speed is 120 MPH I think.......

[Mrs.ssippi]

Blue? No, no the answer is yellow. Yes, yellow and that is my final answer. Wait, can I use my phone a friend?

[Wisha Haddan H3]

Yes for self-propelled airplanes but No for gliders towed behind ground vehicles.

In self-propelled airplanes thrust is delivered from the props or jets directly to the air, not to the ground. Since no forward thrust is delivered through the wheels, the conveyor will remain stationary. In fact, the conveyor may even move forward slightly with the plane depending on the amount of friction from the axles and the tire's contact patch. As the plane moves forward through the air, relative airspeed increases, lift is generated on the wings and the plane takes off.

With gliders, thrust is provided by a tow vehicle. If the tow vehicle is a truck on the conveyor, it would deliver its thrust through the wheels to the conveyor. Forward movement would be negated by the conveyor's movement, resulting in zero forward motion. The truck could be going 100 mph (relative to the conveyor) but its airspeed and groundspeed (next to the conveyor) would still be 0. No air would pass over the glider's wings and no lift would be generated for takeoff.

[PARAGON]

Originally Posted by Wisha Haddan H3

Yes for self-propelled airplanes but No for gliders towed behind ground vehicles.

In self-propelled airplanes thrust is delivered from the props or jets directly to the air, not to the ground. Since no forward thrust is delivered through the wheels, the conveyor will remain stationary. In fact, the conveyor may even move forward slightly with the plane depending on the amount of friction from the axles and the tire's contact patch. As the plane moves forward through the air, relative airspeed increases, lift is generated on the wings and the plane takes off.

With gliders, thrust is provided by a tow vehicle. If the tow vehicle is a truck on the conveyor, it would deliver its thrust through the wheels to the conveyor. Forward movement would be negated by the conveyor's movement, resulting in zero forward motion. The truck could be going 100 mph (relative to the conveyor) but its airspeed and groundspeed (next to the conveyor) would still be 0. No air would pass over the glider's wings and no lift would be generated for takeoff.

Nope

keep trying

[CO Hummer]

How do you figure the plane can take off when there is no wind moving over the wings to create lift? Can't happen.