ThinAirDesigns
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Actually, it's much easier to understand where he's coming from when he doesn't respond.
JB
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Split Thread The validity of classical physics (split from: DWFTTW)
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Actually, it's much easier to understand where he's coming from when he doesn't respond.
JB
All the information that you need is in the question, or in this thread. There is an answer. I have not had one answer from any of you, that is nothing more that "all velocities are relative".
See if you can put that to work on my problem.
GregLondon
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Even if we assume that humber will never get newtons three laws, its not that big a deal. Assuming he isn't designing aircraft or rockets or some life critical component for some project, there's no harm in not understanding physics. A phrase from Hitchhiker's Guide comes to mind: "mostly harmless".
It's frustrating because you want him to understand. But then some folks take the frustration and turn it around and start figuring out how to show humber he is wrong. I don't think humber is doing it on purpose, though, so I'm not going to hold it against him that I can't explain it to him.
The "taking a cart and slowing it down with a fishing reel to figure out the air resistance" problem? I read it. I think it's over my head.
I'd look at it from finding the point where the cart can't go any faster, and that would tell you that the force from friction is equal to teh force from the prop/wheel. Since I think it should be possible to calculate the force from the prop/wheel for a given speed (I don't know how to do it, which is why its over my head), once you know what speed no longer has acceleration, I think you then know what the force from friction is at that speed.
I suppose if you want to measure the force of resistance at any other speed, you could do it by adding some kind of adjustable brake so you can add a resistance force to the cart to keep it from accelerating. Once you know that force, you should be able to throw that into the equations so that force from teh prop/wheel = force of friction + force from brake.
Either that, or measure the acceleration of the cart at the speed, and using f=ma maybe figure out what force is left over after friction to accelerate the cart.
So, either I'd add a braking force so that there is no accelaration and then all the forces have to balance and the only unknown would be friction, OR, measure acceleration and figure out what force is left over after friction to accelerate the cart. Either way, you need to be able to calculate the force from teh prop/wheel, and although that seems calculable based on prop-pitch, diameter, efficiency, and the gear ratio between the prop and wheel, I don't know how to od that part.
I'm not a prop guy.
You don't need to be. It's just a sail cart. No prop.
Uote
Now you know another reason why I don't answer quizzes.
My personal career is not important.
ETA:
As I mentioned earlier, Greg, I am not interested in the cart. yo-yo's are a distraction.
Then you won't want to hear what I have to say. OK
I understand, but don't agree. Your arguments are false, Greg. They are like TAD's.
The question is itself, wrong, yes.
Yes, it tests itself.
Too many dependent variables, yes.
Now you know another reason why I don't answer quizzes.
My personal career is not important.
ETA:
As I mentioned earlier, Greg, I am not interested in the cart. yo-yo's are a distraction.
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I keep having this humorous image of Humber "retiring" from the space program after providing NASA with his analysis of why it would be impossible for two spacecraft to dock in orbit.
"What about the KE?? My god, those things mass many thousands of kilograms, and they're each traveling at 27000 kph! When they touch, blammo, it's game over!"
Tunny
GregLondon
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I haven't asked you any questions to try to get you to fail anything.
Well, I don't know what you mean by "maximum power theorem". I thought if you worked in "blah", I could google for "maximum power theorem" and "blah".
You don't ahve to say what you do for a living, but you still haven't said what you meant by "maximum power theorem". The only definition I know is a EE definition, and it has to do with chosing sizes of resisters in a circuit, not newtonian objects interacting with each other.
Can you explain what you meant by "maximum power theorem"?
What does that leave? You're only interest is that a treadmill isn't a valid test?
If that's it, then why did you pretty much ignore my scenario with the windmill on the groudn generating one kilowatt in a 10 mph wind, and the same windmill mounted on a giant treadmill moving at 10 mph indoors (no wind) also generating one kilowatt?
I seem to remember you saying they weren't equivalent for some reason.
Does this whole thread come down to you disbelieving in inertial frames?
How does one go about proving that the cart on the ground in a tailwind is the same as teh cart on a treadmill indoors, that they are both equivalent inertial frames, if you don't care about the cart and the yoyo is a distraction?
I offered the windmill in a 10 mph wind, and a windmill on a treadmill moving at 10 mph, to show that in either case, the windmill will generate the same amount of power. But then you seemed to bring the discussion back to why the cart woudln't work. So you're not interested in the cart but you're interested in the cart.
If it's just inertial frames, the windmill in 10 mph wind and the windmill on a 10mph treadmill should be sufficient to show the two are equivalent. Do you disagree that the windmill would put out the same amount of power in these two scenarios?
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Subduction Zone
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humber seems to be the sort of person that googles a lot of scientific sites but does not pick up the knowledge in them, just a few terms. Time after time he has used technical terms incorrectly, too often to site here, his use of "maximum power theorem" is just the latest in a long chain. Since he practically never answers a direct question, and on the few times he has he has almost always been wrong, I have put him on selective ignore. If he puts too much blathering nonsense in one of his posts I tend to skip over it. You will get no more joy in arguing with humber than you would have with a brick wall, and you will get about the same amount of useful information out of it.
Actually you don't understand, despite all my efforts to help you. You manage to prove that almost every time you post. The only thing you have been right about is that there is no point to testing you. I know what the results will be. And I think you know that too, hence your handy excuses for not answering anything.
sol invictus
Philosopher
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Whatever.
You're a compete and utter waste of time, and more importantly you've ceased entertaining me for the moment, so I'm done.
Once in a while he does. It's usually pretty perplexing to try to read it. It looks like he's writing in English, until you try to make sense of any of it. That's some of the best stuff, there.
Ah Mr Humber, though you were not explicit, by the fact you responded and are still posting, I think it is wonderful, our first agreement! You do not believe it would be fine for the outcome of your body to crash a car into another one, even with the precaution of being mid-air and not "grounded". I know it was a trivial and banal contrivance of an experiment, I didn't mean to insult our intelligence, just wanted to establish a baseline. I was a little confused about your velocity and kinetic energy principles. I think I see now what you were getting at, since perhaps just after the collision, there may be no kinetic energy or velocity of either car with respect to each-other if we set things up well, but then (for metal cars at least) they would fail to pass each-other, silly test!
Perhaps I could entertain you with a better experiment. Would you be willing to try this one? I will be "driving" a large SUV. You will be "riding" a motorcycle. We will be doing 150mph as read on our respective speedometers, but don't worry, with respect to the room we are in, we will be stationary. It will be a rather large room though, and the entire floor will be the belt surface of a very massive and powerful treadmill. Now, you are "riding" just next to me, say 1 meter to my left. Would you want your helmet on? Is there any chance of something going wrong? If, perhaps I sneeze and inadvertently swerve left, surely with only a meter separating us I would not collide with you at a great rate. And anyway, neither vehicle has kinetic energy wrt the earth, apart from the rotating stuff, but we'd just use our brakes to get rid of that, wouldn't we? What techniques could we use to analyse and try to predict if this is safe?
Can we do this Mr Humber, please?
Perhaps I could entertain you with a better experiment. Would you be willing to try this one? I will be "driving" a large SUV. You will be "riding" a motorcycle. We will be doing 150mph as read on our respective speedometers, but don't worry, with respect to the room we are in, we will be stationary. It will be a rather large room though, and the entire floor will be the belt surface of a very massive and powerful treadmill. Now, you are "riding" just next to me, say 1 meter to my left. Would you want your helmet on? Is there any chance of something going wrong? If, perhaps I sneeze and inadvertently swerve left, surely with only a meter separating us I would not collide with you at a great rate. And anyway, neither vehicle has kinetic energy wrt the earth, apart from the rotating stuff, but we'd just use our brakes to get rid of that, wouldn't we? What techniques could we use to analyse and try to predict if this is safe?
Can we do this Mr Humber, please?
CORed
Penultimate Amazing
Because the toy car doesn't have a propeller geared to the wheels and it's on a piece of paper, not a treadmill belt. Too easy.
... has been reduced to...
Wow! What happened to all the other stuff you mentioned earlier? Where's the "no significant KE from any frame" and "cart 'balance'" stuff? Does their omission from this new list mean you have withdrawn those earlier claims? (That would be sensible in my opinion, but you should tell us so we know, and you did say you would.)
In any case, it's not up to me to refute your crazy (but occasionally amusing) fantasies. "Extraordinary claims require extraordinary proof." (Actually, even a tiny shred of proof would be a start in your case.) You are the (very) odd one out here. It's up to you make some kind of coherent arguments to support your various claims. Instead you have demonstrated an uncanny ability to string words together in more or less meaningless sentences for a couple of months on end, but not much else.
Anyway, let's look briefly at at the first item on your new list:
"1, Paddle wheel. (No)"
What is that paddle wheel all about? In my view it is a completely unnecessary complication (introduced by you of course). It seems to be a only a very roundabout way to describe the difference in velocity for two "layers" in the air above the treadmill belt and road. Why not just subtract one "1-dimensional velocity" (using signs for direction) from the other? You have to do that anyway to determine what your paddle is going to do! This all relates to your claim that the behaviour of some part of the boundary layer above the treadmill belt relative to the non-boundary layer air higher above that would be significantly different to what would be seen in the "equivalent" road scenario. (Same wind, surface type, etc.) Something (never clearly described) was "going the wrong way" according to you.
The ball is in your court on this, and has been for a long time. John Freestone presented you with several straightforward questions about the issue, and I (and probably others) put similar questions to you before that. We had to do that because nobody could understand any of your garbled attempts to explain yourself before that. You've made no serious attempt to respond to John's questions, or the earlier ones. Why? It seems pretty obvious to me - you can't answer without looking like a complete idiot. You have to either persevere with your original fantasy in the face of the results from a thought experiment that a five year could probably follow, or shoot yourself in the foot by suddenly agreeing with what everybody else has been telling you all along. In other words, that the flows above the belt and above the road, relative to the road or belt respectively, are essentially identical in all cases.
So, if you "seriously" want to resolve the boundary layer question (hah-hah), then respond to those questions. In the absence of any coherent and logical response, I will continue to observe that you are apparently incoherent and illogical (and increasingly non-responsive also).
Let's get that first one out of the way before wasting any more time on the others.
Yes, Greg, that is what my little exercise is about. A sail cart in a ten mph wind. A fishing reel with a brake. Zero force measured on the scale when the cart is at 9 mph. A braking force applied to slow the cart to 8 mph, and a reading taken (arbitrarily 100 grams). From that and an understanding of the physics involved, the answer is - what? Humber couldn't get it but you are on the right track.
Quote: Greg London
'It's frustrating because you want him to understand. But then some folks take the frustration and turn it around and start figuring out how to show humber he is wrong. I don't think humber is doing it on purpose, though, so I'm not going to hold it against him that I can't explain it to him'
Really? Poor benighted humber. ( I need to add this, for others)
Perhaps you could (all) learn something before trying to teach me?
It is about power transfer in general, Greg, not only electrical. See Carnot Cycle, thermodynamics, load matching, load lines...
Electrical analogues are common practice in a wide range of disciplines.
Use them. http://www.eas.asu.edu/~holbert/analogy.html
Here is some forum chat on the topic. Some people have trouble with abstracted ideas.
http://www.eng-tips.com/viewthread.cfm?qid=159381&page=76
"CFD" works for heat flow too.
You have to learn it, to understand it. It does not come in internet forum bites. It is quite common to find professionals who do not understand first principles. They 'learned' but that was all.
Yes.
Patently true. Why would you even bother to mention it? Did you expect that I would be surprised?
Heth'etheth's fish tank. Looks at drawing...mmm...cam on the floor, trailing castor operates sluice (gate)...so that goes CCW...text below says fish comes from right....OK...so that's how it works...
Imagine possible variants. Two minutes, perhaps?
Nothing like the treadmill, not even close !
They are not "equivalent", but would generate much the same power. And?
No. Inertial frames are not applicable. It's about the machine that is the treadmill, and that makes false appeals to that idea. Sounds impressive at Arby's, though.
By proving that the cart is doing what it looks like it is doing. Almost motionless, spinning its propeller. Anything beyond that is imaginary.
Another way it to pick up the treadmill and drive the generator prop directly with the belt. And?
Not interested in the cart, but the treadmill/cart.
Why not? Is this idea the wonder of the ages? All motion is relative. How else?
In fact, should you not be surprised at the result? Isn't your 'real' wind generator moving 1000km/hr as the Earth rotates?
Perhaps that is also true of the one on the treadmill too...perhaps its only the local difference that matters...
There you go. A full course in "inertial frames of reference". In this thread, an idea about nothing.
Do you all not understand that this is utterly orthodox? "Ground power" is one thing that is refuted by that same precept.
The power is generated by the action of the wind on the prop. That is 100% of what is available. Wind/prop and wind/ground are not two separate identities.
The idea of relative motion, is inflated to cover every possible situation but without any support. Mostly assumption, and knee-jerk reaction.
Yes. Spork's silence is golden
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