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NORDHAVN Rewrites Physics Textbooks
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Stephen Trapani wrote: Richard Casady wrote: On Sun, 14 Oct 2007 20:37:22 -0700, Stephen Trapani wrote: The advertisement never claimed to impart forward force going directly into the wind. All they claimed was that they could somehow decrease the load on the motor or increase the efficiency of the system. Those two sentences mean the same thing. Raising a sail when headed directly into the wind will increase the aerodynamic drag acting on the boat, and reduce speed. Putting wings on a plane increases aerodynamic drag acting on the plane, yet it increases the speed, right? Stephen Actually, NO, putting wings on the plane does NOT increase its speed, unless one considers the difference in Drag due to Alltitude. If putting wings, on increased the speed, then missiles would have wings, which they don't. Duh...... |
NORDHAVN Rewrites Physics Textbooks
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NORDHAVN Rewrites Physics Textbooks
Gravity does not exist at the LaGrangian point.
Yes it does. Gravity always exists. At a LaGrange point, the gravity of one mass is cancelled by the mass of another. So gravity has no effect on free bodies at a LaGrange point, but gravity still exists. "Bill" wrote: How does one know it exists there? By measuring it? Or by postulating it? If gravity of one mass is cancelled by another then it does not exist, the net force is zero. There is a big difference between "does not exist" and "net force = zero." ... Zero means nothing. Anyway, you are completely wrong. Gravity can be higher at a Lagrangian point provided it is countered by acceleration forces. It says so on this NASA website: So, you said gravity doesn't exist, now you say that it not only may exist but that those who know most about it say it is greater; then you say that I'm "completely wrong." Good work. I look forward to your help and comments with my replies to your scientifically astute and accurate commentary. It's not often we get someone here who really knows their **** and is willing to help others. Thanks immensely. You're welcome immensely. DSK |
NORDHAVN Rewrites Physics Textbooks
On 15 Oct, 17:46, "Bill" wrote:
"toad" wrote in message ps.com... On 15 Oct, 14:27, (Richard Casady) wrote: Why wouldn't it accellerate indefinitely with no friction anywhere in the system. ....because as it approaches the speed of light it will require infinate energy. My flashlight shoots out photons at the speed of light and it is powered by a 1 1/2 volt battery. Even better, my flashlight moves away from the photons at the speed of light with the same 1 1/2 volt battery. If you are saying you flashlight moves at the speed of light relative to you, I'm impressed. If your flashlight moves at the speed of light relative to it's own output I'm less impressed! |
NORDHAVN Rewrites Physics Textbooks
On 15 Oct, 17:56, "Bill" wrote:
"toad" wrote in message ups.com... On 15 Oct, 16:20, "Bill" wrote: "toad" wrote in message The guy who built the windmill boat could be a lying crackpot. I have not seen one with my own eyes so your point is valid. You wouldn't have to lie. Natural wind isn't all in one direction. You could be steaming ahead in your windmill boat on the components of the wind that are not directly on the nose and really believe yourself to be sailing upwind. Pyro actually posted a picture of his cart working - but in the photo he was blowing downwards on it. He wasn't lying, he realy did think it was going upwind, he just didn't have a handy head protractor! It's also worth noting that some of the windmill craft identified in the course of this 'debate' as craft that could sail directly into wind turn out to be incapable of going direct into wind! It's a futile to debate this in words. We need figures. It will be resolved one day when somebody who genuinely knows (as opposed to guessing based on gut feeling and justifying it with wordy posts using analogies) simply posts the worked formula to prove it one way or the other. You only have to look at the Conundrum thread to realize just how much of a pinch of salt you have to take with armchair physicists on usenet! If the windmill did work we could put small wind turbines on bicycles and reduce the pedaling load for cyclists and even increase their speeds into strong headwinds. Forget that, you could put windmills on the bonnets of sports cars, gear their output to the drive and turn that 100mph headwind into even more power. |
NORDHAVN Rewrites Physics Textbooks
On Sun, 14 Oct 2007 11:57:47 -0700, toad
wrote: On 14 Oct, 19:38, Andy Champ wrote: Same speed *relative to the the surface it is on*. Yes, so you accept it has spare energy left over after it has overcome the drag of the windmill. So the windmill on the foredeck of our power boat has enough energy to push against the wind pushing back on it. It also has enough energy left over after this to move it forwards. Which means you can gear that spare energy to the engine and save some petrol. Yet you and I both accept you can't do that. So there's a paradox. In other words there is some spare energy left over to drive the cart forwards after the energy required to hold the windmill in equilibrium with the wind is expended. In my example above that spare energy is used to drive the cart forwards but in your example of the windmill on the foredeck that surplus energy can be used to save petrol. Now we both accept that idea is laughable so you have to explain why it's not laughable when the wind blowing is caused by nature. ...but most importantly, why oh why oh why doesn't someone just post the mathmatical proof, the last time this came up I said I'd leave the thread 'till proof turned up and none did. Odd that. Lets take this step by step. Or to put it another way "Lets take this step by step so I can keep talking rather than posting the maths that I claim is simple to prove my case." Do you accept that it is possible for the cart to move directly upwind? It is essential that we assume that to be the case so you can explain the paradox exposed by the windmill on powerboat example. If in a headwind the windmill pushes back harder than it is pushed then it must do that no matter how that headwind comes about. Which leaves us with a power boat with a windmill on it's foredeck getting a net gain in energy from wind that it is creating. No it gets energy from a reduction of the kinetic energy of the _true_ wind. |
NORDHAVN Rewrites Physics Textbooks
wrote in message ups.com... On 15 Oct, 17:46, "Bill" wrote: "toad" wrote in message ps.com... On 15 Oct, 14:27, (Richard Casady) wrote: Why wouldn't it accellerate indefinitely with no friction anywhere in the system. ....because as it approaches the speed of light it will require infinate energy. My flashlight shoots out photons at the speed of light and it is powered by a 1 1/2 volt battery. Even better, my flashlight moves away from the photons at the speed of light with the same 1 1/2 volt battery. If you are saying you flashlight moves at the speed of light relative to you, I'm impressed. If your flashlight moves at the speed of light relative to it's own output I'm less impressed! My flashlight is not that impressive. If it gave off enough photons it could move at the speed of light relative to me. |
NORDHAVN Rewrites Physics Textbooks
"Ian" wrote in message ups.com... On 15 Oct, 14:19, (Richard Casady) wrote: On Sun, 14 Oct 2007 23:31:30 -0700, Ian wrote: What force do you think does work against gravity to allow aeroplanes to ascend? Thrust from the engine, of course. Nope. How many aircraft do you think are capable of vertical takeoff? A Boeing 747-400 has a take off weight of 875,000 lbf and a total thrust of 4 x 63,300 = 253,200 lbf. My own aircraft has a take off mass of 370kg and no thrust whatsoever, and yet I can get it to go up. Ian But in your example, gravity is still causing you to descend through the air. Unless converting excess speed to height, you only climb because the air in which you are flying is rising faster than your sink rate. Presumably, if a boat's motion is generating apparent wind from dead ahead and a fully battened sail (I say fully battened because it's a better aerofoil shape) could be set far enough out to achieve sufficient angle of attack to produce some lift, then a keel boat "may" go a little quicker. Would the lift produced be greater than the drag though? Graham. |
NORDHAVN Rewrites Physics Textbooks
On Mon, 15 Oct 2007 07:31:20 -0700, Stephen Trapani
wrote: Putting wings on a plane increases aerodynamic drag acting on the plane, yet it increases the speed, right? Absolutely not. For the highest possible speed you use the smallest wing you can get away with. You do have to land. A bigger wing is favored for short takeoff and landing, for example. A bigger wing will make for a steeper angle of climb, at a slower speed. To increase rate of climb, more engine power is needed. No free lunch anywhere, a good rule to remember. The only real way to increase performance in all areas, is to make it lighter. You can have strong, light, or cheap. Pick any two. Casady |
NORDHAVN Rewrites Physics Textbooks
wrote in message ups.com... Gravity does not exist at the LaGrangian point. Yes it does. Gravity always exists. At a LaGrange point, the gravity of one mass is cancelled by the mass of another. So gravity has no effect on free bodies at a LaGrange point, but gravity still exists. "Bill" wrote: How does one know it exists there? By measuring it? Or by postulating it? If gravity of one mass is cancelled by another then it does not exist, the net force is zero. There is a big difference between "does not exist" and "net force = zero." Yes there is. But how does one tell the difference? ... Zero means nothing. Anyway, you are completely wrong. Gravity can be higher at a Lagrangian point provided it is countered by acceleration forces. It says so on this NASA website: So, you said gravity doesn't exist, now you say that it not only may exist but that those who know most about it say it is greater; then you say that I'm "completely wrong." Good work. The good work goes to you. You've parsed out all of the previous thread to only the above point. Why is that? You said gravity cancels at the Lagrangian point. I said it does not exist. For simplicity let's throw away the L2, L3... Langrangian points and deal with just the L1 point since it can be argued that in a first order case there is no net gravity at that point. Agreed? You say the gravity there exists but it cancels to zero. I say the gravity does not exist because it is zero. Of course we are talking of the total or net gravitational field at a point in space. Now if you were in a black box at the L1 point and not aware of the external cicrumstances and took out your gravitometer and measured zero what would your conclusion be? Would it be there is no field here (Occam's razor) or would you conclude that there are bodies nearby in such arrangement to have their fields cancel? Remember you are in a black box. So tell me of an experiment to be performed at a single point in space that can resolve all the gravitational vectors upon that point. Is there no gravity at the center of the earth or is there lots of gravity that just happens to cancel to zero? Since when does the quantity zero imply the existence of anything? As far as being completely wrong, you are. Here is a bit on the LaGrangian point: http://en.wikipedia.org/wiki/Lagrangian_point "The Lagrange points mark positions where the combined gravitational pull of the two large masses provides precisely the centripetal force required to rotate with them." This is not what you said, you only considered gravity. I look forward to your help and comments with my replies to your scientifically astute and accurate commentary. It's not often we get someone here who really knows their **** and is willing to help others. Thanks immensely. You're welcome immensely. I'd like to be regraded. You said: "In other words, "Bill" you flunked the physics test and you don't know as much as you think you do." But you didn't know who Milliken was, you believed he was like the Amazing Kreskin; you weren't aware of Einstein saying the gravity field ceases to exist for an observer in a free fall; you mistook my single clock running at two different rates for two different observers as 2 clocks in different inertial frames, disagreed with what I said and then essentially restated what I said to make your point; you failed to account for the increase in oscillation velocity of a photon in a gravitational free fall even though its translational speed remains constant; you have not defended your position that not all realized energy involves movement, which it does; you claim that things exist when measured to be zero and exhibit no effect what so ever on test particles. In view of these oversights on your part would you kindly regrade the physics test? I am but a simple student/observer of natural philosophy seeking direction. I'll gladly admit any mistakes I have made if you kindly point them out. I just don't see how I deserve a failing grade or how you can possible estimate how much I think I know about physics.The bottom line is it's not what you think you know, it's what you can prove, measure and demonstrate. I tried to do that with all the points we disagreed upon to the best one can do in a single USENET post. It now seems the only point left with which we disagree is that you say: Even though gravity measured is zero it is really there but cancels itself. And I say: If gravity is measured to be zero, it (gravity) does not exist at the point of measurement. My statement is the fundamental law of identity A---A A is A. A being "zero" or "non existence". Your argument is A----A+*A. This essentially says that A can be itself plus elements that are not itself. Carrying it one step further by making A to be zero, you are making nothing to be made up of constituent elements that when added make it zero, but the elements are still there, existing beyond all senses and measurement. entia non sunt multiplicanda praeter necessitatem Bill |
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