Merged DDWFTTW in a “Real” Wind

[jduffy77]

Humber, could your balloon use the balloon/wind speed differential as a power source?

 

[humber]

I believe this quote from Humber sums up his confusion best. He seems to truly believe that Energy of motion is absolute and not wrt to an IRF.

KE is always computed wrt to a chosen IRF and it is different in any other linear translating but valid IRF.
Humber, we can't state this enough and if you do not understand it, there's not much to discuss.

Quoting text is not understanding text, Windgrins.
Quadratic functions may not be linearly added. I can't state this enough, and if you do not understand it, there's not much to discuss.
KE is not relative without bound, and there are rules that you have ignored in the soundbite.

An object that has a -ve velocity still has a "positive" KE (-v)^2 = V^2. If that is then converted by transform(-v)^2 = -1(V)^2, at it may, then all other derived KE's must be similarly transformed.
KE is energy, and if that transform is ignored or haphazardly applied, then the Sun can become a refrigerator.

The Kinetic Energy of an object moving in two linear translating reference frames is two different values. KE is a score keeping system for physics. COE is a statement of what to always expect from this score keeping system.

The scorekeeper may not swap teams, nor call a strike a home run.

This is why when you riding in your car down the street at 60 kph, from the frame of reference of the driver, the car has no energy wrt to the driver.

And the same applies at the stop lights.

From the reference frame of the pedestrian you just hit, the car has significant energy.

Same as from the driver's view, or any curious by-stander's. However, it will be certain that the pedestrian did not drink the gasoline that powered the car to give it that KE.

This is our disconnect and I don't think we'll get past it.
WindGrins

How about your Epiphany, really was a blind date with her cranky sister, Tiffany?

 

[spork]

I think I know your position and it goes a bit like this:

As a balloon enters into the flow of air the balloon experiences aerodynamic drag that tends to pull the balloon to the speed of the air....

Yup. For a neutrally buoyant balloon, you got it exactly. If the balloon has positive or negative buoyancy, there can be other interesting factors as it ascends or descends through gradient (nothing that wouldn't be obvious to you).

More interesting perhaps is that the balloon even tracks wind gusts very well. Intuition might suggest the balloon takes time to come up to the new wind speed, but this isn't the case.

 

[windgrins]

Neutrally Buoyant Balloons as wind gust indicators

Yup. For a neutrally buoyant balloon, you got it exactly. If the balloon has positive or negative buoyancy, there can be other interesting factors as it ascends or descends through gradient (nothing that wouldn't be obvious to you).

More interesting perhaps is that the balloon even tracks wind gusts very well. Intuition might suggest the balloon takes time to come up to the new wind speed, but this isn't the case.

That makes sense. For a neutrally buoyant balloon, the mass properties are the same as the displaced air so the volume should react just the same.

Interesting. I hadn't thought of that!

WindGrins

 

[spork]

For a neutrally buoyant balloon, the mass properties are the same as the displaced air so the volume should react just the same.

Interesting. I hadn't thought of that!

WindGrins

I posted a little test I did on this: http://www.youtube.com/watch?v=johyzKImRTw

 

[windgrins]

Spork's Non-Humberian Balloon

I posted a little test I did on this: http://www.youtube.com/watch?v=johyzKImRTw

Spork,

Actually that was an excellent demo also with the smoke. I really liked the non-symmetric weighting to demonstrate the validity of the mass properties issue also. You read my mind before I had the thought! Now that's a neat trick.

Anyone want to take any bets that some poster(s) will argue that the air inside the car with the windows rolled up is not a valid example of "wind" over the earth so the demo proves nothing? 3 to 1 odds for this statement at the moment.

You guys look like traffic menaces out there! I'll be on the lookout if I'm in the Bay area driving!

PS, I have a trivial brainteaser (so don't give it away Spork):

What if you tether a lighter than air helium balloon to the floor of the car and a heavier than air balloon to the ceiling of the car side by side and then do the heavy accelerating and breaking as well as curve tests.
What will be the behaviour of the balloons? I'll even be willing to do the video for this one if we don't agree.

Regards,

WindGrins

 

[Subduction Zone]

No, it says below. I need not bother to explain against simple and blunt denial.
The balloon matter has been settled in my favour, for many reasons, including Spork's failure to support his Aero degree.

Yes, you do. You never settled this question at all. Others pointed out your errors to you at the time. And since even you know that you are obviously wrong about the balloon moving faster than the wind you have never touched the problem. You can claim that you have won all that you want, but I seriously doubt that you can convince even you about that. You have not convinced anyone else.

 

[Dr. Keith]

Presumes its conclusion. You may as well make the blanket statement that all objects will achieve WS.

Yes, I was stating a position.

No news there. The balloon achieves a point of dynamic, but not static stability, and that is below WS.

Why below?
How far below?
How is this difference calculated in the most simple case you can imagine?
I'd really like to understand your position better.

Over-simplification, is a euphemism for something even worse: total ignorance resulting from hubris.

I think hubris would have been saying that I knew I was right. I haven't said that, I've merely stated what I understand to be right in a simple hypothetical.

"Drag force", can the result of the air decelerating against the object when it is said to be driving that object (e.g tailwind). That is the basis of Rayleigh's drag formula, derived from Newton's impact theorem, which considers the deceleration of an air molecule against the surface of a mass, which is large compared to the molecular mass; such as a balloon or sail.

OK

"Opposing drag" is the result of the air decelerating against the same object, but from the opposite direction (e.g. headwind). Of course, if the object is not already in motion, that headwind is a "tailwind" but in the other direction.
"Upwind" and "downwind" are only a means of expressing motion relative to that medium. It's the same wind.

OK

If that same object travels in air that is not in motion, then there is neither a tailwind or headwind, but there is opposing drag that is a result of the object accelerating the air ahead of it. ( as a car does). That applies to above WS too, where the cart is said to be faster than the slower air ahead of it.
The difference only lies in the initial velocity of the air relative to the cart.

Again, not how I would say it but OK.

A consequence of Galilean Relativity, a natural outcome of Newton's laws of motion, means that the drag force on the balloon, is also a drag force on the air, but in the opposite direction as Newton's 3rd Laws says.

So, in a system where the air is moving and the balloon is moving slower than the air the drag will be accelerating the balloon and also slowing down some air. If that's what you mean I think I can agree.

There can simply never be a point where one can drag or push the other such that the result is zero.

Why not? as the balloon is pulled by the air at WS it approaches WS. the drag is constantly reducing as the balloon gets closer and closer to WS until the balloon is at WS.

The reason there is no defense is luminous.

I should hope. Please share.

 

[Dr. Keith]

Yup. For a neutrally buoyant balloon, you got it exactly. If the balloon has positive or negative buoyancy, there can be other interesting factors as it ascends or descends through gradient (nothing that wouldn't be obvious to you).

Thanks. Professor Koshmeider will be happy I retained some of his hydraulics.

More interesting perhaps is that the balloon even tracks wind gusts very well. Intuition might suggest the balloon takes time to come up to the new wind speed, but this isn't the case.

That is slightly counter intuitive at first but makes complete sense.

 

[Jack by the hedge]

you are trying to claim a two body system, with a third hidden away

Count the rockets.

One rocket... Two rockets.

Hmm. Two rockets.

Is there a third one hidden away somewhere? Nope.

The matter concerned KE, and your method produces errors. The same as those made by so many students. Some correct those, some so not.

It does not sound as if you read and understood what I wrote.
Your method produces gibberish. Everyone else's method models reality. If you doubt this, please attempt to point out these "errors" in the most comprehensible language you can.

 

[Dr. Keith]

The balloon matter has been settled in my favour, for many reasons, including Spork's failure to support his Aero degree.

The balloon mater isn't about spork, it is about your claims regarding neutrally buoyant balloons in a stead wind(aka: uniformly moving medium).

And I don't have an aero degree. A few classes in how water flows, but no credentials. Just questions.

Thanks.

 

[windgrins]

WindGrins Trivial Balloon Teaser

What if you tether a lighter than air helium balloon to the floor of the car and a heavier than air balloon to the ceiling of the car side by side and then do the heavy accelerating and breaking as well as curve tests.
What will be the behaviour of the balloons?



WindGrins

 

[windgrins]

Windgrins Trivial Balloon Teaser

What if you tether a lighter than air helium balloon to the floor of the car and a heavier than air balloon to the ceiling of the car side by side and then do the heavy accelerating and breaking as well as curve tests.
What will be the behaviour of the balloons?

[qimg]http://www.internationalskeptics.com/forums/imagehosting/thum_488654db08df58ab85.png[/qimg]

WindGrins

Spoiler Alert. I don't even have to shoot the video. These guys did a great job of it even though their explanation is a bit lame. They clearly behave as we would expect from our previous experiments/explanations:

http://www.youtube.com/watch?v=aaFn3nh300E

Windgrins

 

[3point14]

How do you measure windspeed?

 

[humber]

Yup. For a neutrally buoyant balloon, you got it exactly. If the balloon has positive or negative buoyancy, there can be other interesting factors as it ascends or descends through gradient (nothing that wouldn't be obvious to you).

Would you like to show your math on that one, Spork?
BTW: Got NALSA data, today. You are toast.

More interesting perhaps is that the balloon even tracks wind gusts very well. Intuition might suggest the balloon takes time to come up to the new wind speed, but this isn't the case.

Newton's F=ma, and v=at, may have something to say about the time is takes....and your intuition, or is it not, this time?

 

[humber]

I posted a little test I did on this: http://www.youtube.com/watch?v=johyzKImRTw

Oh, that one was hilarious. Another example of TAD's experimental abilities.

The smoke won't do what is it supposed to do, so the car jerks forwards, the air sloshes about around the occupants and reflects of the windscreen, until the female occupant can take no more, and leaves.

 

[windgrins]

Humber has the data-Top Secret cart to follow!

Would you like to show your math on that one, Spork?
BTW: Got NALSA data, today. You are toast.

Humber,

Does this mean we get to see the "Top Secret" car in action now that you have the data?

Please post!

Regards,

WindGrins

 

[humber]

Count the rockets.

One rocket... Two rockets.

Hmm. Two rockets.

Is there a third one hidden away somewhere? Nope.

Well, the mass-less observer you are trying to make the center of mass.

It is very funny to see adults defend junior school errors as a new dawn of scientific thinking.

There was no argument about the momentum because m*v is not quadratic, so it can be added as you would like. However, no so KE, because it's quadratic, and and (-v)^ = V^2

Spork is back. Would you like to see him prove his acceleration claim mathematically, like a proper aeronautical engineer rather than silly pet tricks?

 

[humber]

Humber,

Does this mean we get to see the "Top Secret" car in action now that you have the data?

Please post!

Regards,

WindGrins

Oh, there is way more to it than that, isn't there, Spork?

 

[humber]

The balloon mater isn't about spork, it is about your claims regarding neutrally buoyant balloons in a stead wind(aka: uniformly moving medium).

And I don't have an aero degree. A few classes in how water flows, but no credentials. Just questions.

Thanks.

I put an open challenge to Spork to prove that he has the skill to support his claims which are not to be found in any text book.

That he can't do that, says a lot.

Like all of the TM tests that have been ignored.