Mythbusters punk'd whole internet

[spidey07]

Originally posted by: gorcorps

Originally posted by: thepd7

Originally posted by: gorcorps
*serious post*

Good lord I can't believe this is still being debated. It was a bit tough to think of at first but after hearing a good explanation of it from my physics prof it made perfect sense.

The plane will take off normally. Anybody who thinks otherwise is confusing how a plane takes off with how a car moves. A car moves by propelling itself with friction: the tire sticks to the ground and the wheels turn, and because the tires have friction with the ground the turning wheels make the car move. A plane moves by forcing air behind it, the wheels are just there for stability and takeoff/landing. If a treadmill was under the wheels of the plane moving backwards, then the air from the jets/propeller will move the plane at normal speed, the wheels will just be turning twice as fast (the speed of the plane+the speed of the treadmill which matches the plane). From looking at just the plane as a whole it will take off normally, but looking at the wheels they're spinning twice as fast as they normally would.

From a physics point of view it's nearly the same as asking if a plane can take off on smooth ice. A car can't move because of the lack of friction, but a plane wouldn't notice because it doesn't use friction to move.

Has your physics prof ever heard of the Bernoulli Principle?

Yes, but I fail to see how that applies to this. Well I know how it applies and have seen that argument but still fail to see how a moving treadmill will 'negate' the forward motion and airflow. It seems if that argument were right then the plane would act like a car which of course it doesn't.

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

 

[Fenixgoon]

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

 

[Agentbolt]

Originally posted by: spidey07

Originally posted by: gorcorps

Originally posted by: thepd7

Originally posted by: gorcorps
*serious post*

Good lord I can't believe this is still being debated. It was a bit tough to think of at first but after hearing a good explanation of it from my physics prof it made perfect sense.

The plane will take off normally. Anybody who thinks otherwise is confusing how a plane takes off with how a car moves. A car moves by propelling itself with friction: the tire sticks to the ground and the wheels turn, and because the tires have friction with the ground the turning wheels make the car move. A plane moves by forcing air behind it, the wheels are just there for stability and takeoff/landing. If a treadmill was under the wheels of the plane moving backwards, then the air from the jets/propeller will move the plane at normal speed, the wheels will just be turning twice as fast (the speed of the plane+the speed of the treadmill which matches the plane). From looking at just the plane as a whole it will take off normally, but looking at the wheels they're spinning twice as fast as they normally would.

From a physics point of view it's nearly the same as asking if a plane can take off on smooth ice. A car can't move because of the lack of friction, but a plane wouldn't notice because it doesn't use friction to move.

Has your physics prof ever heard of the Bernoulli Principle?

Yes, but I fail to see how that applies to this. Well I know how it applies and have seen that argument but still fail to see how a moving treadmill will 'negate' the forward motion and airflow. It seems if that argument were right then the plane would act like a car which of course it doesn't.

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

Try your little experiment again, but push on the plane slightly in the back. The plane will move forward while the treadmill goes beneath it. Now make the treadmill go a gazillion miles per hour and push it slightly again. Guess what, THE PLANE STILL MOVES FORWARD.

 

[spidey07]

Originally posted by: Fenixgoon

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

Really? Then why is the plane moving backwards with it's engines off? I fully understand that the plane has thrust.

Do you fully understand why the plane moves backwards when there is no thrust? If you do, then you can start to understand.

 

[RapidSnail]

Originally posted by: spidey07

Originally posted by: Fenixgoon

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

Really? Then why is the plane moving backwards with it's engines off? I fully understand that the plane has thrust.

Do you fully understand why the plane moves backwards when there is no thrust? If you do, then you can start to understand.

Because there is no thrust.

 

[gorcorps]

Originally posted by: spidey07

Originally posted by: Fenixgoon

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

Really? Then why is the plane moving backwards with it's engines off? I fully understand that the plane has thrust.

Do you fully understand why the plane moves backwards when there is no thrust? If you do, then you can start to understand.

Well yeah there's a tiny bit of friction in the wheel axles due to the weight of the plane and nothing being perfect, but when you turn the engines on that tiny force is basically moot when the treadmill is matching the plane speed. Now if it's going WAY faster than the plane then the plane doesn't move, but it's not a given that the plane will stay in place regardless of how fast the plane is going.

We're both right as there's a point at which the speed of the treadmill will not allow the plane to move forward, but there's also speeds at which the plane CAN move forward and has the ability to take off.

 

[Agentbolt]

Originally posted by: spidey07

Originally posted by: Fenixgoon

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

Really? Then why is the plane moving backwards with it's engines off? I fully understand that the plane has thrust.

Do you fully understand why the plane moves backwards when there is no thrust? If you do, then you can start to understand.

The transfer of energy from the wheels to the plane is extremely weak, since the wheels are on bearings. If the brakes were on and the wheels were locked up, you'd have a point. But since they're not, you don't.

A very small amount of force can overcome the treadmill's backward motion, because almost NONE of that motion is being transferred to the plane through the wheels.

 

[spidey07]

Originally posted by: Agentbolt
The transfer of energy from the wheels to the plane is extremely weak, since the wheels are on bearings. If the brakes were on and the wheels were locked up, you'd have a point. But since they're not, you don't.

A very small amount of force can overcome the treadmill's backward motion, because almost NONE of that motion is being transferred to the plane through the wheels.

Or course that is true, but you can't discount it as others have continually pretended it isn't there.

But according to the wording of the question the treadmill is capable of instant and infinite acceleration.

 

[randay]

Originally posted by: spidey07

Originally posted by: Agentbolt
The transfer of energy from the wheels to the plane is extremely weak, since the wheels are on bearings. If the brakes were on and the wheels were locked up, you'd have a point. But since they're not, you don't.

A very small amount of force can overcome the treadmill's backward motion, because almost NONE of that motion is being transferred to the plane through the wheels.

Or course that is true, but you can't discount it as others have continually pretended it isn't there.

But according to the wording of the question the treadmill is capable of instant and infinite acceleration.

Then the airplane takes off. Backwards.

 

[Agentbolt]

Originally posted by: spidey07

Originally posted by: Agentbolt
The transfer of energy from the wheels to the plane is extremely weak, since the wheels are on bearings. If the brakes were on and the wheels were locked up, you'd have a point. But since they're not, you don't.

A very small amount of force can overcome the treadmill's backward motion, because almost NONE of that motion is being transferred to the plane through the wheels.

Or course that is true, but you can't discount it as others have continually pretended it isn't there.

But according to the wording of the question the treadmill is capable of instant and infinite acceleration.

It is? I missed the infinite part. Never mind then.

 

[Fenixgoon]

Originally posted by: RapidSnail

Originally posted by: spidey07

Originally posted by: Fenixgoon

Originally posted by: spidey07

It's real simple.

Put an airplane on a treadmill with no engines. Measure the force the plane is moving backward at. Now increase the treadmill to 1 gazillion miles per hour. Measure again, it will be a lot higher.

THIS is what prevents the plane from moving forward. How anybody can say otherwise is beyond me. How can one honestly believe that the wheels and the plane aren't connected?

because the plane's thrust has NOTHING to do with its wheels.

a car's power is sent TO the wheels, a plane's thrust IS NOT.

Really? Then why is the plane moving backwards with it's engines off? I fully understand that the plane has thrust.

Do you fully understand why the plane moves backwards when there is no thrust? If you do, then you can start to understand.

Because there is no thrust.

as an edit: how many people here are aerospace engineers and understand how flight *actually* works?

i've posed this question to my brother, a master's in aerospace engineering, and he affirms the plane will take off. so unless any of you happen to understand the principles of aerodynamics, flight, lift, etc. better than he, please stop claiming the plane will not take off.

only if i could get him to make drawings and explanations.. but i know he won't do that for ATOT, heh.

 

[ITPaladin]

I watched it last night...wrong episode?

There was nothing about this.

 

[FoBoT]

Originally posted by: ITPaladin
I watched it last night...wrong episode?

There was nothing about this.

they had the wrong show notes published, the producer put out a statement saying the PoaT segment would be in the show on Jan 30

 

[thepd7]

Originally posted by: gorcorps

Originally posted by: thepd7

Originally posted by: gorcorps
*serious post*

Good lord I can't believe this is still being debated. It was a bit tough to think of at first but after hearing a good explanation of it from my physics prof it made perfect sense.

The plane will take off normally. Anybody who thinks otherwise is confusing how a plane takes off with how a car moves. A car moves by propelling itself with friction: the tire sticks to the ground and the wheels turn, and because the tires have friction with the ground the turning wheels make the car move. A plane moves by forcing air behind it, the wheels are just there for stability and takeoff/landing. If a treadmill was under the wheels of the plane moving backwards, then the air from the jets/propeller will move the plane at normal speed, the wheels will just be turning twice as fast (the speed of the plane+the speed of the treadmill which matches the plane). From looking at just the plane as a whole it will take off normally, but looking at the wheels they're spinning twice as fast as they normally would.

From a physics point of view it's nearly the same as asking if a plane can take off on smooth ice. A car can't move because of the lack of friction, but a plane wouldn't notice because it doesn't use friction to move.

Has your physics prof ever heard of the Bernoulli Principle?

Yes, but I fail to see how that applies to this. Well I know how it applies and have seen that argument but still fail to see how a moving treadmill will 'negate' the forward motion and airflow. It seems if that argument were right then the plane would act like a car which of course it doesn't.

I'm no aerospace engineer, but isn't the Bernoulli principle the reason planes fly?

So you need wind rushing by the wings for lift, right?

Whenever I run on a treadmill I don't feel the wind rushing by because I am essentially not moving relative to most of the air around me.

So no wind, Bernoulli Principal not working, no lift, no take off.

This is what my simpleton EE brain has come up with.

 

[FoBoT]

air does pass over the wings, as the plane moves down the treadmill

the question isn't what is needed for lift, it is does the plane move or stay still

since the wheels are free wheeling and the engine thrust pushes on the air and not the treadmill, then the plane moves down the treadmill. the relative motion between the air and the wing means lift is created and the plane takes off, after it has traveled down the runway far enough to get up to take off speed

 

[RapidSnail]

Originally posted by: Fenixgoon
as an edit: how many people here are aerospace engineers and understand how flight *actually* works?

i've posed this question to my brother, a master's in aerospace engineering, and he affirms the plane will take off. so unless any of you happen to understand the principles of aerodynamics, flight, lift, etc. better than he, please stop claiming the plane will not take off.

only if i could get him to make drawings and explanations.. but i know he won't do that for ATOT, heh.

You don't even need to be an aerospace engineer to understand this.

Air flow creates lift. Air flow comes from motion. Plane's motion is derived from its thrusters. Motion created by thrusters is not restricted by freely moving wheels.

 

[edro]

Originally posted by: thepd7

Originally posted by: gorcorps

Originally posted by: thepd7

Originally posted by: gorcorps
*serious post*

Good lord I can't believe this is still being debated. It was a bit tough to think of at first but after hearing a good explanation of it from my physics prof it made perfect sense.

The plane will take off normally. Anybody who thinks otherwise is confusing how a plane takes off with how a car moves. A car moves by propelling itself with friction: the tire sticks to the ground and the wheels turn, and because the tires have friction with the ground the turning wheels make the car move. A plane moves by forcing air behind it, the wheels are just there for stability and takeoff/landing. If a treadmill was under the wheels of the plane moving backwards, then the air from the jets/propeller will move the plane at normal speed, the wheels will just be turning twice as fast (the speed of the plane+the speed of the treadmill which matches the plane). From looking at just the plane as a whole it will take off normally, but looking at the wheels they're spinning twice as fast as they normally would.

From a physics point of view it's nearly the same as asking if a plane can take off on smooth ice. A car can't move because of the lack of friction, but a plane wouldn't notice because it doesn't use friction to move.

Has your physics prof ever heard of the Bernoulli Principle?

Yes, but I fail to see how that applies to this. Well I know how it applies and have seen that argument but still fail to see how a moving treadmill will 'negate' the forward motion and airflow. It seems if that argument were right then the plane would act like a car which of course it doesn't.

I'm no aerospace engineer, but isn't the Bernoulli principle the reason planes fly?

So you need wind rushing by the wings for lift, right?

Whenever I run on a treadmill I don't feel the wind rushing by because I am essentially not moving relative to most of the air around me.

So no wind, Bernoulli Principal not working, no lift, no take off.

This is what my simpleton EE brain has come up with.

The reason a plane flies is because the propeller pulls it through the volume of air... not because the wheels drive it along.
The plane will be pulled through the air, regardless of what the wheels are doing.
The plane will move forward.
The plane will take off.

No, the plane cannot simply rise vertically, like a Harrier Jet... it still must move forward to generate the lift described by the Bernoulli principle.

 

[spidey07]

Not so. The plane simply cannot move forward. Impossible. Can't happen. No matter how much force you think you have, the treadmill accelerates even quicker to maintain the position.

If not, then you have cheated and no longer adhering to the question at hand.

 

[RapidSnail]

Originally posted by: thepd7
I'm no aerospace engineer, but isn't the Bernoulli principle the reason planes fly?

So you need wind rushing by the wings for lift, right?

Whenever I run on a treadmill I don't feel the wind rushing by because I am essentially not moving relative to most of the air around me.

So no wind, Bernoulli Principal not working, no lift, no take off.

This is what my simpleton EE brain has come up with.

Except your feet are not equivalent to the plane's wheels because your feet supply power to your body frame. You would be right if the plane's wheels provided motion to the plane, but they do not. If you strapped a a horizontal jet pack to yourself and jumped on the treadmill with a pair of rollerblades, you would no doubt feel air flow.

 

[FoBoT]

the treadmill doesn't transfer its force to the airplane. only to the rotating wheel

and the treadmill only matches the speed of the plane as it moves, not the speed of the wheel.

 

[RapidSnail]

Originally posted by: spidey07
Not so. The plane simply cannot move forward. Impossible. Can't happen. No matter how much force you think you have, the treadmill accelerates even quicker to maintain the position.

If not, then you have cheated and no longer adhering to the question at hand.

What's the question? You're obviously using a different one than anyone else in this thread.

 

[thepd7]

Originally posted by: RapidSnail

Originally posted by: thepd7
I'm no aerospace engineer, but isn't the Bernoulli principle the reason planes fly?

So you need wind rushing by the wings for lift, right?

Whenever I run on a treadmill I don't feel the wind rushing by because I am essentially not moving relative to most of the air around me.

So no wind, Bernoulli Principal not working, no lift, no take off.

This is what my simpleton EE brain has come up with.

Except your feet are not equivalent to the plane's wheels because your feet supply power to your body frame. You would be right if the plane's wheels provided motion to the plane, but they do not. If you strapped a a horizontal jet pack to yourself and jumped on the treadmill with a pair of rollerblades, you would no doubt feel air flow.

well shit it sounds like I can solve this problem by experimenting on my own, I'm off!

 

[Fritzo]

I don't understand the debate on this in the first place---if a plane is on a conveyor belt, only the belt and the wheels on the plane would be moving. It's the compression of air underneath the wings that causes flight---since the conveyor belt is not forcing the air around the wings, the plane would not be able to take off. If the conveyor had some kind of paddles attached to it to move air, it could cause enough lift, or if there were a huge fan in front of the plane it could cause lift, but moving wheels under a plane will do nothing.

Is there some other aspect of this I'm missing?

 

[Darwin333]

Originally posted by: thepd7

Originally posted by: gorcorps

Originally posted by: thepd7

Originally posted by: gorcorps
*serious post*

Good lord I can't believe this is still being debated. It was a bit tough to think of at first but after hearing a good explanation of it from my physics prof it made perfect sense.

The plane will take off normally. Anybody who thinks otherwise is confusing how a plane takes off with how a car moves. A car moves by propelling itself with friction: the tire sticks to the ground and the wheels turn, and because the tires have friction with the ground the turning wheels make the car move. A plane moves by forcing air behind it, the wheels are just there for stability and takeoff/landing. If a treadmill was under the wheels of the plane moving backwards, then the air from the jets/propeller will move the plane at normal speed, the wheels will just be turning twice as fast (the speed of the plane+the speed of the treadmill which matches the plane). From looking at just the plane as a whole it will take off normally, but looking at the wheels they're spinning twice as fast as they normally would.

From a physics point of view it's nearly the same as asking if a plane can take off on smooth ice. A car can't move because of the lack of friction, but a plane wouldn't notice because it doesn't use friction to move.

Has your physics prof ever heard of the Bernoulli Principle?

Yes, but I fail to see how that applies to this. Well I know how it applies and have seen that argument but still fail to see how a moving treadmill will 'negate' the forward motion and airflow. It seems if that argument were right then the plane would act like a car which of course it doesn't.

I'm no aerospace engineer, but isn't the Bernoulli principle the reason planes fly?

So you need wind rushing by the wings for lift, right?

Whenever I run on a treadmill I don't feel the wind rushing by because I am essentially not moving relative to most of the air around me.

So no wind, Bernoulli Principal not working, no lift, no take off.

This is what my simpleton EE brain has come up with.

Think about how much force is required when you are running on your treadmill.

Now, go grab you a pair of rollerskates, strap em on and turn the treadmill up to the same speed. How much force do you think it will require to overcome the friction of the wheels and stay in the same place (holding on to the handle). How much force will it require to pull yourself forward at 1mph? How fast are the wheels actually traveling when you pull yourself forward at a relative speed of 1mph? If the treadmill is going 10mph is your body going 10mph in reverse or are the wheels on the skates the only thing going 10mph?

If the wind is blowing fast enough a plane can take off without the wheels ever moving.

A passenger jet can theoretically "hover" in midair and land without the wheels ever moving if the wind is blowing fast enough.

Aside from real world factors like friction and the limits of the wheel assembly the wheels have nothing to do with the thrust the engines produce and the air moving over the wings

 

[Darwin333]

Originally posted by: Fritzo
I don't understand the debate on this in the first place---if a plane is on a conveyor belt, only the belt and the wheels on the plane would be moving. It's the compression of air underneath the wings that causes flight---since the conveyor belt is not forcing the air around the wings, the plane would not be able to take off. If the conveyor had some kind of paddles attached to it to move air, it could cause enough lift, or if there were a huge fan in front of the plane it could cause lift, but moving wheels under a plane will do nothing.

Is there some other aspect of this I'm missing?

Yes. The thrust produced from the jet engines.