MythBusters

[smack Down]

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: DanTMWTMP
I've never seen a more dense person who refuses to thoroughly read anything than Jandrews.

The argument isn't about wind going over the wings. It's about the plane moving foward in relation to a point outside of the threadmill/plane model. In relation to this point, the plane moves forward as if the treadmill is nonexistent. Numerous youtube videos already show that the plane moves foward. Engines act on the air, not on the ground.

A Car WILL stay stationary
A plane will not.

I have no idea why you are so stupidly dense not to realize this utterly simple riddle.

You are completely wrong. A Car and plane will behave identical on a treadmill.

AS for the physics lets pretend that we have two cars that have the same mass(m), same moment of inertia(i), and no friction. For the sake of simplicity lets take the acceleration at 1 m/s/s

On a road do you agree that they would reach a speed of 1 m/s after one second of driving? and both have the same amount of kinetic energy? 1 * m + 1 * i

Ok now lets put our two cars on the same treadmill. Your theory is the the rocket car will still accelerate at 1 m/s/s (or some other value greater then zero) and the engine car will accelerate at 0 m/s/s (that is stay in place). Correct? Additional you claim that the treadmill will be going backwards at a minimum of 1 m/s/s (In reality it would be going faster then this. The speed depends on the mass of the car. 1 m/s/s is only true with a car of zero mass.)

The rocket car energy is 1 * m + i * (1 + Vtreadmill)^2.
The normal car has an energy is 0 *m + i * Vtreadmill^2

Remember that in the 1 second on the road they had the same energy and now the rocket car has much more energy when both are required to be equal and equal to the original 1 * m + 1 * i. There is no way a plane can behave differently then the car.

err, we are talking about how the energy is used. car torques the wheels to move forward, plane does not torque the wheel to move forward. Otherwise we would have no airplanes!

Energy isn't used it is converted from one form to another. Just explain how the plane gets the additional energy.

again, a car uses its wheel to move. In your example, the normal car would expend said energy to counter the treadmill. Rocket car is not torquing its wheel. The wheel moves because of the hot exhaust coming out the business end of the rocket. It's not about extra energy, it's about how the energy is used.


PS energy is being used all the time. Just because the mechanics is actually conversion to other form doesn't stop it from being used.

Where did the energy go that the car "expend" what object had its velocity increased? There are only two object that can have their velocity increased the car and the car wheels.

 

[smack Down]

Originally posted by: rikadik

Originally posted by: smack Down

Originally posted by: rikadik

Originally posted by: smack Down

So where is the energy going in your theory? It can't just dissipate?

The energy is making the wheels spin. That's where the energy is going. It's really not difficult to understand. But the wheels cannot use their energy to create a forward force on the car as there is essentially no friction with the treadmill! There is no lost energy - the car's kinetic energy is just in the wheels spinning faster and faster.

A plane however converts most of its energy into air rushing out of the engines causing a forward force on the plane.

But if you're such a physics genius (and not just a trolling retard like most suggest) then why don't YOU explain where the energy produced by the engines is going in the plane situation if you claim it sits still?

What the hell do you mean there is no friction? There is infinite friction the tires do not slip.

Actually - what I was meaning to say is it is like having no friction.

I'm not suggesting that the tires slip, but just that because the treadmill is moving backwards at say 1 m/s, if the car applies the power to the wheels it would do to move forward on tarmac at 1 m/s, the car remains stationary. Just like as if there was no friction between the tires and tarmac on a normal road.

But the car isn't the point is it - we both agree its not going to move.

It doesn't take power for the car to drive at 1 m/s. Power implies an acceleration of the car . You are think of a car with its engine off now think of one with its engine on.

 

[Cold Steel]

Originally posted by: smack Down


It doesn't take power for the car to drive at 1 m/s. Power implies an acceleration of the car .

umm... no.

Acceleration is a change in velocity. Power is the amount of work being done over time. It takes power for a car to drive at 1m/s, but if the car is steady at 1m/s, there is no acceleration.

 

[smack Down]

Originally posted by: Cold Steel

Originally posted by: smack Down


It doesn't take power for the car to drive at 1 m/s. Power implies an acceleration of the car .

umm... no.

Acceleration is a change in velocity. Power is the amount of work being done over time. It takes power for a car to drive at 1m/s, but if the car is steady at 1m/s, there is no acceleration.

Work is the change in potential energy the potential energy of the car. There is no change when the car is driving at a constant speed on level ground.

 

[sdifox]

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: DanTMWTMP
I've never seen a more dense person who refuses to thoroughly read anything than Jandrews.

The argument isn't about wind going over the wings. It's about the plane moving foward in relation to a point outside of the threadmill/plane model. In relation to this point, the plane moves forward as if the treadmill is nonexistent. Numerous youtube videos already show that the plane moves foward. Engines act on the air, not on the ground.

A Car WILL stay stationary
A plane will not.

I have no idea why you are so stupidly dense not to realize this utterly simple riddle.

You are completely wrong. A Car and plane will behave identical on a treadmill.

AS for the physics lets pretend that we have two cars that have the same mass(m), same moment of inertia(i), and no friction. For the sake of simplicity lets take the acceleration at 1 m/s/s

On a road do you agree that they would reach a speed of 1 m/s after one second of driving? and both have the same amount of kinetic energy? 1 * m + 1 * i

Ok now lets put our two cars on the same treadmill. Your theory is the the rocket car will still accelerate at 1 m/s/s (or some other value greater then zero) and the engine car will accelerate at 0 m/s/s (that is stay in place). Correct? Additional you claim that the treadmill will be going backwards at a minimum of 1 m/s/s (In reality it would be going faster then this. The speed depends on the mass of the car. 1 m/s/s is only true with a car of zero mass.)

The rocket car energy is 1 * m + i * (1 + Vtreadmill)^2.
The normal car has an energy is 0 *m + i * Vtreadmill^2

Remember that in the 1 second on the road they had the same energy and now the rocket car has much more energy when both are required to be equal and equal to the original 1 * m + 1 * i. There is no way a plane can behave differently then the car.

err, we are talking about how the energy is used. car torques the wheels to move forward, plane does not torque the wheel to move forward. Otherwise we would have no airplanes!

Energy isn't used it is converted from one form to another. Just explain how the plane gets the additional energy.

again, a car uses its wheel to move. In your example, the normal car would expend said energy to counter the treadmill. Rocket car is not torquing its wheel. The wheel moves because of the hot exhaust coming out the business end of the rocket. It's not about extra energy, it's about how the energy is used.


PS energy is being used all the time. Just because the mechanics is actually conversion to other form doesn't stop it from being used.

Where did the energy go that the car "expend" what object had its velocity increased? There are only two object that can have their velocity increased the car and the car wheels.

normal car yes, but not a rocket car. Rocket car depends on thrust, not torquing the wheels. The whole rocket car is being propelled forward from the reaction of the exhust.

 

[Cold Steel]

Originally posted by: smack Down

Work is the change in potential energy the potential energy of the car. There is no change when the car is driving at a constant speed on level ground.

Again, umm..... no. Potential energy is the energy stored by position. A drawn bow has potential energy. A car moving at 1m/s is not storing energy as a function of it's position.

 

[rikadik]

Originally posted by: smack Down
It doesn't take power for the car to drive at 1 m/s.

It does under some circumstances - i.e., when you're not driving your car in space.

 

[ConstipatedVigilante]

I think you guys are explaining this in an overly complicated manner. The main part of the thing is that many seem to think that the wheels' motion correlates to the plane's motion. It does not. The wheels' motion is completely separate from that of the plane. They are on axles which allow them to spin freely, but have absolutely no connection to the force of the plane's engines. They spin freely when going forward on a regular runway because the ground under them is still, and they must move to reduce friction. In the case of the treadmill, they spin with the treadmill to negate the effect it would have on the plane if the plane were on, say, skis. The skis would produce a ton of friction because they would be directly attached to the plane, and would be pushed in two directions at once, and the plane would not move. But the wheels are separate from the plane on their own axles of rotation. They can spin backwards while the plane moves forwards.

 

[smack Down]

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

Originally posted by: DanTMWTMP
I've never seen a more dense person who refuses to thoroughly read anything than Jandrews.

The argument isn't about wind going over the wings. It's about the plane moving foward in relation to a point outside of the threadmill/plane model. In relation to this point, the plane moves forward as if the treadmill is nonexistent. Numerous youtube videos already show that the plane moves foward. Engines act on the air, not on the ground.

A Car WILL stay stationary
A plane will not.

I have no idea why you are so stupidly dense not to realize this utterly simple riddle.

You are completely wrong. A Car and plane will behave identical on a treadmill.

AS for the physics lets pretend that we have two cars that have the same mass(m), same moment of inertia(i), and no friction. For the sake of simplicity lets take the acceleration at 1 m/s/s

On a road do you agree that they would reach a speed of 1 m/s after one second of driving? and both have the same amount of kinetic energy? 1 * m + 1 * i

Ok now lets put our two cars on the same treadmill. Your theory is the the rocket car will still accelerate at 1 m/s/s (or some other value greater then zero) and the engine car will accelerate at 0 m/s/s (that is stay in place). Correct? Additional you claim that the treadmill will be going backwards at a minimum of 1 m/s/s (In reality it would be going faster then this. The speed depends on the mass of the car. 1 m/s/s is only true with a car of zero mass.)

The rocket car energy is 1 * m + i * (1 + Vtreadmill)^2.
The normal car has an energy is 0 *m + i * Vtreadmill^2

Remember that in the 1 second on the road they had the same energy and now the rocket car has much more energy when both are required to be equal and equal to the original 1 * m + 1 * i. There is no way a plane can behave differently then the car.

err, we are talking about how the energy is used. car torques the wheels to move forward, plane does not torque the wheel to move forward. Otherwise we would have no airplanes!

Energy isn't used it is converted from one form to another. Just explain how the plane gets the additional energy.

again, a car uses its wheel to move. In your example, the normal car would expend said energy to counter the treadmill. Rocket car is not torquing its wheel. The wheel moves because of the hot exhaust coming out the business end of the rocket. It's not about extra energy, it's about how the energy is used.


PS energy is being used all the time. Just because the mechanics is actually conversion to other form doesn't stop it from being used.

Where did the energy go that the car "expend" what object had its velocity increased? There are only two object that can have their velocity increased the car and the car wheels.

normal car yes, but not a rocket car. Rocket car depends on thrust, not torquing the wheels. The whole rocket car is being propelled forward from the reaction of the exhust.

It doesn't matter where did the energy go/come from to make one car have a different velocity. They both converted the same amount chemical energy to mechanical now what makes up for the difference in final energy. What other object changed its velocity to/give take energy to make up for the change.

 

[Eeezee]

Originally posted by: smack Down

Originally posted by: Eeezee
Sorry, I missed the original question and don't feel like looking for it. What energy are you talking about?

Originally posted by: Eeezee

Originally posted by: Maiora

What does that have to do with anything? So you can move faster then a treadmill what is your point?

Why hasn't the mod banned this fucking waste of oyxgen yet? Of course the plane will move forward you fucktard. Just get the fuck out of this thread fucking already. You're making everyone that reads it have an IQ drop worse than the stock market. Jesus Fucking Christ! :|

If there was a name for ignorance of science it would be your middle fucking name!

He just misunderstands, it's not like that's breaking forum rules. Science is about asking questions and making observations. He just hasn't made enough observations to understand that his hypothesis is wrong.

Hey so you missed the question but no the answer is wrong?

I missed the specific question about energy. That has nothing to do with the fact that he thinks the airplane won't take off. That is wrong.

Was that not clear?

 

[Eeezee]

Originally posted by: Jeff7

Originally posted by: Eeezee

Originally posted by: Jeff7
Really? Where is it debated? At least at subsonic speeds, I thought it was pretty well figured. Supersonic speeds, then things get a bit weird.

Link

Maybe the very basics of an airfoil are understood, but the exact understanding of the airflow on a very small level is the problem. Or if you want exact calculations, then you might have to factor in that oh-so-fun phenomenon: turbulence. Good old chaotic, inherently unpredictable, turbulence.


In any event, on a standard passenger jet or single-engine plane, it's the wing shape that produces lift when air flows over it. In a plane like a Cessna, yes, the propeller happens to push air over the wings, but not nearly enough to take off - otherwise, a Cessna would be a vertical-takeoff aircraft. It's the motion of the plane through the air, with sufficient speed, that lets the airfoil work its magic.

I believe that if the propeller were pushing enough air over the wings, it really could be a vertical-takeoff aircraft (massive/powerful propeller). What's the difference between the airplane moving through the air and air moving across the wings? There isn't any.

Just one little difference - an airplane moving through the air has a velocity component perpendicular to the direction of lift.
So a forward moving airplane is indeed a vertical takeoff machine, assuming your frame of reference is a point moving at the same forward speed as the aircraft. From that perspective, there is no difference.

Scenario A - Plane is motionless relative to the earth, giant fan blows air at plane and over wings
Scenario B - Plane moves relative to the earth, through the air, causing air to travel of the wings

If you take your frame of reference to be the plane's pilot, then there is no difference between scenarios A and B. In both cases there is no velocity component because in the pilot's reference frame, the plane is stationary (even if it is moving relative to the earth). As such, there is no difference between the two scenarios because physics works the same in all reference frames (and between them assuming non-relativistic speeds)

 

[Eeezee]

Originally posted by: 91TTZ
You're talking about wings and ignore angle of attack. There are quite a few morons who think that wings needs to have the classic airfoil shape in order to produce lift. A wing could be perfectly flat and produce lift by by changing the angle of attack of that wing.

Apples and oranges. Calling people morons for describing how an airfoil works is moronic.

 

[Eeezee]

Okay, now I kind of understand your concerns over energy, but I think they're unnecessary concerns. Some problems are easily solved with energy. Some are easily solved with forces. Some are easily solved with a constrained Lagrangian (a combination of forces and energy). In this case, a free body diagram is all you need (ie solve with forces).

Here we go then

A car exerts energy to spin its wheels. The act of the wheel spinning causes a friction force pointing in the opposite direction of the rotation. Thus, the car accelerates forward due to the friction between the ground and the wheel.

A plane uses energy to push air, thus creating a forward force.

As you can see, these are two different ways to accelerate an object. Consider a plane without wheels; it has skis instead. That is effectively the same situation; the plane eventually overcomes the friction between itself and the conveyor belt and accelerates forward, eventually taking off.

Ultimately, it doesn't matter whether or not the planes has wheels. Those wheels are not connected to whether the plane can move.

 

[cHeeZeFacTory]

i'm just waiting for the show to end with "plausible".

 

[ConstipatedVigilante]

Actually, a plane with skis couldn't take off on the conveyor belt. In that case the conveyor belt would be counteracting the speed of the plane, not the wheels. The skis are directly attached to the body of the plane, while the wheels are not.

 

[PurdueRy]

Originally posted by: ConstipatedVigilante
Actually, a plane with skis couldn't take off on the conveyor belt. In that case the conveyor belt would be counteracting the speed of the plane, not the wheels. The skis are directly attached to the body of the plane, while the wheels are not.

Actually...it could.

Yes, it is then imparting a force on the plane. However, the force is just the static friction force(changing to sliding friction) which is small enough that I imagine most any place engine could overcome.

As the plane moved faster the lift generated would counteract the normal force causing the friction force to further decrease and the plane to accelerate further.

 

[ConstipatedVigilante]

Ok, so in that case it's just a much less graceful, more smoky, more skidd-y take-off.

 

[sdifox]

Originally posted by: smack Down

It doesn't matter where did the energy go/come from to make one car have a different velocity. They both converted the same amount chemical energy to mechanical now what makes up for the difference in final energy. What other object changed its velocity to/give take energy to make up for the change.

how you apply the energy has everything to do with the problem. Say your car heats up and become incandecent, ie a light bulb, would it move forward? no, because the energy is being spent on conversion to heat/light.

PS even my accountant wife thinks it will take off.

 

[BeauJangles]

Smackdown, read up on my scenario and please tell me what happens to the plane.

Please explain what happens in this scenario:

-A plane takes off from a normal runway and leaves its landing gear extended.
-The plane circles around to a secondary runway which is a giant conveyor belt moving backward (ie, 180 degrees opposite the plane's forward motion) at the same ground speed the plane has (if the plane is flying at 180 mph, the conveyor is moving at 180 mph in the opposite direction).
-The plane, without slowing down, flies low enough that its landing gear touches the conveyor belt, but does not attempt to land.

 

[PurdueRy]

Originally posted by: ConstipatedVigilante
Ok, so in that case it's just a much less graceful, more smoky, more skidd-y take-off.

Yup

:evil:

 

[gsellis]

Originally posted by: BlinderBomber
Smackdown, read up on my scenario and please tell me what happens to the plane.

Please explain what happens in this scenario:

-A plane takes off from a normal runway and leaves its landing gear extended.
-The plane circles around to a secondary runway which is a giant conveyor belt moving backward (ie, 180 degrees opposite the plane's forward motion) at the same ground speed the plane has (if the plane is flying at 180 mph, the conveyor is moving at 180 mph in the opposite direction).
-The plane, without slowing down, flies low enough that its landing gear touches the conveyor belt, but does not attempt to land.

Don't bother. He is like a parrot. He knows the words, but does know what they mean.

 

[91TTZ]

Originally posted by: Eeezee

Originally posted by: 91TTZ
You're talking about wings and ignore angle of attack. There are quite a few morons who think that wings needs to have the classic airfoil shape in order to produce lift. A wing could be perfectly flat and produce lift by by changing the angle of attack of that wing.

Apples and oranges. Calling people morons for describing how an airfoil works is moronic.

How can you say that this is an "apples and oranges" comparison? I think that people just revert to that useless saying when they have nothing else to say.

 

[smack Down]

Originally posted by: sdifox

Originally posted by: smack Down

It doesn't matter where did the energy go/come from to make one car have a different velocity. They both converted the same amount chemical energy to mechanical now what makes up for the difference in final energy. What other object changed its velocity to/give take energy to make up for the change.

how you apply the energy has everything to do with the problem. Say your car heats up and become incandecent, ie a light bulb, would it move forward? no, because the energy is being spent on conversion to heat/light.

PS even my accountant wife thinks it will take off.

So your saying the car heats up? That is your solution? Sorry but my car has no friction so it doesn't heat up. Where did the energy go.

 

[BeauJangles]

Originally posted by: smack Down

So your saying the car heats up? That is your solution? Sorry but my car has no friction so it doesn't heat up. Where did the energy go.

If you're such a physics guru, then you'll have no problem explaining to me what happens in the scenario I outlined above. You're talking about excess energy, which I make no pretension to understand, but I'm just asking you to answer a simple thought problem. It shouldn't be very hard for you to provide a satisfactory explanation. Please feel free to use as many equations and numbers as you'd like.

Eagerly awaiting your response!

 

[sdifox]

Originally posted by: smack Down

Originally posted by: sdifox

Originally posted by: smack Down

It doesn't matter where did the energy go/come from to make one car have a different velocity. They both converted the same amount chemical energy to mechanical now what makes up for the difference in final energy. What other object changed its velocity to/give take energy to make up for the change.

how you apply the energy has everything to do with the problem. Say your car heats up and become incandecent, ie a light bulb, would it move forward? no, because the energy is being spent on conversion to heat/light.

PS even my accountant wife thinks it will take off.

So your saying the car heats up? That is your solution? Sorry but my car has no friction so it doesn't heat up. Where did the energy go.

wtf are you smoking??? You said it doesn't matter where the energy goes and I tell you it matters. The light bulb is an example why how the energy is used is important.