Mythbusters punk'd whole internet

[LTC8K6]

Those of you who use the car analogy...

What if we strap a jet engine to the roof of the car?

Will the jet engine be able to move the car forwards?

 

[spidey07]

Originally posted by: LTC8K6
Those of you who use the car analogy...

What if we strap a jet engine to the roof of the car?

Will the jet engine be able to move the car forwards?

No. Because if it does then the wheels are moving faster than the treadmill, breaking the condition that they are identical.

 

[jandrews]

the jets help but since there is no wind going under the wings I dont see how it will attain lift off. When a plan moves the air moves under it's wings at an increasing rate and without that wind to provide additional lift it will stay on the ground. With really powerful jets angled towards the ground a bit more it may be possible but as it stands the plane would not take off.

 

[LTC8K6]

No, the condition is not broken. The treadmill still speeds up.

The jet will easily overcome the wheel friction and move the car forward.

The speed of the treadmill is irrelevant for all practical purposes. The car with the jet engine for thrust will not be able to tell the difference between the treadmill and a highway.

Same for any plane.

Anyone who thinks the plane can't take off on the treadmill must think planes can't take off at all.

Let's play some more.

Suppose the plane does not start on the treadmill, but starts one foot away from it.

The plane begins to move, and in one foot it reaches the surface of the running treadmill.

What will happen?

Will the plane stop when it's wheels begin to rotate backwards?

Will the plane just keep going?

It will just keep going and take off normally, save for some excess landing gear wheel rotation speed.

 

[LTC8K6]

the jets help but since there is no wind going under the wings I dont see how it will attain lift off. When a plan moves the air moves under it's wings at an increasing rate and without that wind to provide additional lift it will stay on the ground. With really powerful jets angled towards the ground a bit more it may be possible but as it stands the plane would not take off.

What will stop the plane from moving forwards? The only thing it can possibly be is the friction in the wheel bearings, which is negligible.

There is essentially nothing to stop the plane from moving.

 

[jandrews]

Originally posted by: LTC8K6

the jets help but since there is no wind going under the wings I dont see how it will attain lift off. When a plan moves the air moves under it's wings at an increasing rate and without that wind to provide additional lift it will stay on the ground. With really powerful jets angled towards the ground a bit more it may be possible but as it stands the plane would not take off.

What will stop the plane from moving forwards? The only thing it can possibly be is the friction in the wheel bearings, which is negligible.

There is essentially nothing to stop the plane from moving.

ok, well put me on a treadmill with wheels on my shoes, there is no wind at all, i am stationary, I dont get what you are trying to get at.

 

[LTC8K6]

Go to the airport with one of those suitcases on wheels.

See if it is difficult to push it against the direction of one of those moving sidewalks.

Don't stand on the the sidewalk yourself, so you don't confuse the issue.

It's not hard at all. It's easy. All you have to overcome is the wheel bearing friction.

The only difference is that the bag's wheels spin faster.

Otherwise it's the same effort as pushing the bag on a stationary sidewalk.

 

[spidey07]

Originally posted by: LTC8K6

the jets help but since there is no wind going under the wings I dont see how it will attain lift off. When a plan moves the air moves under it's wings at an increasing rate and without that wind to provide additional lift it will stay on the ground. With really powerful jets angled towards the ground a bit more it may be possible but as it stands the plane would not take off.

What will stop the plane from moving forwards? The only thing it can possibly be is the friction in the wheel bearings, which is negligible.

There is essentially nothing to stop the plane from moving.

Except the treadmill matching the speed of the wheels. That prevents it from moving.

You keep trying to sidestep the bounds of the problem and ignore the very real force acting against the plane.

I say again - the plane will move backwards with no thrust applied. Speed up the treadmill and the plane moves backwards faster with no thrust applied. That right there proves what everybody is forgetting. Sure it's very small, but it's there.

Now match the speed of the treadmill to the speed of the wheels identically and by the very definition of the question it cannot advance no matter how much force you apply.

 

[Fenixgoon]

Originally posted by: spidey07

Originally posted by: LTC8K6

the jets help but since there is no wind going under the wings I dont see how it will attain lift off. When a plan moves the air moves under it's wings at an increasing rate and without that wind to provide additional lift it will stay on the ground. With really powerful jets angled towards the ground a bit more it may be possible but as it stands the plane would not take off.

What will stop the plane from moving forwards? The only thing it can possibly be is the friction in the wheel bearings, which is negligible.

There is essentially nothing to stop the plane from moving.

Except the treadmill matching the speed of the wheels. That prevents it from moving.

You keep trying to sidestep the bounds of the problem and ignore the very real force acting against the plane.

I say again - the plane will move backwards with no thrust applied. Speed up the treadmill and the plane moves backwards faster with no thrust applied. That right there proves what everybody is forgetting. Sure it's very small, but it's there.

Now match the speed of the treadmill to the speed of the wheels identically and by the very definition of the question it cannot advance no matter how much force you apply.

again - the wheels will spin freely on a plane. it's not like a car where the wheels are attached to axles driven by the driveshaft.

 

[LTC8K6]

"ok, well put me on a treadmill with wheels on my shoes, there is no wind at all, i am stationary, I dont get what you are trying to get at. "

Okay, you are on a treadmill wearing roller skates.

I will play the airplane's thrust and stand to the side with my hand on your back.

We will start the treadmill and I will hold you still, matching the treadmill's effort to move you backwards via the friction in the wheel bearings.

Can I push you forwards?

Yep.

No matter how fast the treadmill runs, I can easily hold you still and easily push you forwards. The only thing trying to move you backwards is wheel bearing friction, which is tiny.

Now, it's not non-existant, so you will go backwards without some forward thrust to hold you still, but the effort is very low.

If I stop pushing you, you will go backwards, but only because of that little bit of friction in the bearings.

Look at it another way.

How hard would it be for you to hold yourself in place on the treadmill while wearing roller skates? It's easy. Therefore, it's easy to push you forwards.

The airplane will not even notice the treadmill.

 

[LTC8K6]

"Except the treadmill matching the speed of the wheels. That prevents it from moving."

How? The wheels are free spinning.

I can take a model car and and hold it still on a running treadmill easily. I can easily push the model car forwards. There's pretty much nothing keeping me from pushing the car. The spinning wheels certainly won't bother me any.

The pilot would only need to add a little additional thrust to keep the plane still.
Otherwise, his takeoff would be normal.

 

[zoiks]

pfft. You guys are all wrong. The plane stays put and the treadmill takes off.

 

[LTC8K6]

If we had magical truly frictionless bearings, the plane would not even move backwards when the treadmill was running. With frictionless bearings, the conveyor belt cannot move the plane at all in either direction.

The only thing affecting the plane is the wheel bearing friction, for all realistic scenarios.
The engine of the plane can easily overcome that friction.

 

[MasonLuke]

Its OBVIOUS the plane will NOT take off. If you want the proof, do a search under the same subject.

The End.

 

[LTC8K6]

The part about the treadmill matching the speed of the wheels or the plane was added to confuse people. It's irrelevant.

 

[LTC8K6]

"Its OBVIOUS the plane will NOT take off."

What is keeping it from taking off?

 

[gorcorps]

Originally posted by: LTC8K6
"Its OBVIOUS the plane will NOT take off."

What is keeping it from taking off?

His faulty logic

 

[GuitarDaddy]

This should be a standard question asked when applying for a drivers license, the applicants should then be seperated by how they answer this question. Everyone that answers "the plane takes off" goes through a door where they take their picture and issue them a license, those that answer "the plane doesn't take off" are lead through a door into a huge meat grinder and eliminated from society

 

[mugs]

Originally posted by: LTC8K6
"Its OBVIOUS the plane will NOT take off."

What is keeping it from taking off?

MasonLuke is a troll, ignore him. IIRC, he has been banned in the past because of his posts in a thread on this topic. You're not going to get anywhere with him. Logic, reason and physics will get you nowhere.

Don't bother with most of these people... if they don't get it after two or three explanations, they're not ever going to accept reality. Take smack down for instance - he knows the outcome of on Mythbusters is not going to match his opinion, so he tried to discredit it before the show even started.

There are plenty of very valid analogies that you can test yourself - the suitcase on a moving walkway is a good one. Rollerblades + rope on a treadmill is an excellent analogy. If people close their mind to reality, you won't get anywhere with them.

 

[Fenixgoon]

Originally posted by: mugs

Originally posted by: LTC8K6
"Its OBVIOUS the plane will NOT take off."

What is keeping it from taking off?

MasonLuke is a troll, ignore him. IIRC, he has been banned in the past because of his posts in a thread on this topic. You're not going to get anywhere with him. Logic, reason and physics will get you nowhere.

Don't bother with most of these people... if they don't get it after two or three explanations, they're not ever going to accept reality. Take smack down for instance - he knows the outcome of on Mythbusters is not going to match his opinion, so he tried to discredit it before the show even started.

There are plenty of very valid analogies that you can test yourself - the suitcase on a moving walkway is a good one. Rollerblades + rope on a treadmill is an excellent analogy. If people close their mind to reality, you won't get anywhere with them.

what's the suitcase one? don't think i've heard that.

 

[mugs]

Originally posted by: Fenixgoon

Originally posted by: mugs

Originally posted by: LTC8K6
"Its OBVIOUS the plane will NOT take off."

What is keeping it from taking off?

MasonLuke is a troll, ignore him. IIRC, he has been banned in the past because of his posts in a thread on this topic. You're not going to get anywhere with him. Logic, reason and physics will get you nowhere.

Don't bother with most of these people... if they don't get it after two or three explanations, they're not ever going to accept reality. Take smack down for instance - he knows the outcome of on Mythbusters is not going to match his opinion, so he tried to discredit it before the show even started.

There are plenty of very valid analogies that you can test yourself - the suitcase on a moving walkway is a good one. Rollerblades + rope on a treadmill is an excellent analogy. If people close their mind to reality, you won't get anywhere with them.

what's the suitcase one? don't think i've heard that.

LTC8K6 posted it about 15 posts up.

I posted another one that you can't really duplicate yourself. Put a car on a treadmill with only the free-spinning wheels on a treadmill. That treadmill can spin all it wants, it's not going to prevent the driving wheels from pulling/pushing the car off the treadmill. The driving wheels are equivalent to the jet engines of the airplane - their force is NOT applied to the treadmill. The free-spinning wheels are equivalent to the free-spinning wheels on a plane. The treadmill can spin those wheels all it wants, but the minimal friction is not going to hold the car back or the plane back.

Spidey is right that the plane would move backward on the treadmill if the engines were not on. That's because there is friction in the wheels. But it is not nearly enough to hold the plane back.

 

[LTC8K6]

In order to stop the plane from moving, the treadmill must supply an equal force on the airplane opposite to the force of the engine.

How does the treadmill apply backwards thrust to the airplane to counter the forward thrust of the engine when the wheels are free to spin?

 

[spidey07]

And in order for it to move forward the wheels have to go faster than the treadmill.

This is NOT allowed. If it is then the treadmill is not matching the speed of the wheels.

 

[MasonLuke]

Originally posted by: LTC8K6
Those of you who use the car analogy...

What if we strap a jet engine to the roof of the car?

Will the jet engine be able to move the car forwards?

Good question and easy to visualize. Those that think the car will move forward are the same ones that think the plane will fly. It is fact that the car cannot move forward. The only way the car can move forward is by the wheels turning. The treadmill counters the wheels spin and keeps the car stationary. Easy to visualize right?

Good Day =)

 

[LTC8K6]

The original question has the treadmill matching the speed of the plane, not the speed of the plane's wheels.

The question makes no sense if the treadmill matches the speed of the plane's wheel rotation. Wheel speed is in RPM and conveyor speed is in MPH. How do you match them?

Somebody got the question wrong along the way.

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

This model plane does not even notice the treadmill.

Neither would a real plane.