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NORDHAVN Rewrites Physics Textbooks
In article ,
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. |
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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. |
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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 |
NORDHAVN Rewrites Physics Textbooks
wrote in message ups.com... 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. I have a scheme for tapping into the power of the rotating earth. I even built an apparatus that worked for several years. Michael Faraday built a small scale device working on the same principle. It is not perpertual motion or any crackpot scheme. It does slow down the rotation of the earth a little and causes local weather changes (on a very small scale). Bill |
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toad wrote:
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. Is that yes? 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. OK. Let's assume wind at 1m/s (I like metric - but that's about 2 1/4 MPH)) and a nice simple force on the windmill of 1000n. (~10Kg, or 20lbs - ish) Neglecting losses, you get a kilowatt out of the mill - 1000n at 1 m/s. Suppose you use that kilowatt to pull the anchor cable. Again, neglecting losses, it ought to be able to pull the winch in at 1m/s, because the force is the drag on the mill. However, you do have losses. Say the whole system loses half the power (in drag on the boat, turbulence around the blades, losses in the generator, etc) You can then wind in the winch at only 1/2 m/s. Now it doesn't matter how much you lose, you will still have some power, and you will still be able to wind the winch in. Back to the 50% loss case. You're winding the winch at 0.5 m/s, and the wind is 1 m/s. Hey look, the apparent wind has gone up - you get more power. Yup, as the force has gone up to 2.25 the original value (it's proportional to the square of the wind speed) and the speed has gone up - so the available power is now the cube of 1.5, a tad over 3. You can wind the winch in faster, the wind goes up, you're away. EXCEPT the drag went up too - by 2.25 times - and as the speed goes up, the power goes up too. You'll find it more than cancels out - which was the point of the spreadsheet I posted the other day. It's a bit different with a prop in the water, not a winch, because a prop. will require some power just to hold still - but not fundamentally different. Now the windmill on the deck of the power boat - lets stick with the 1000n force & 1m/s. (OK - Canal boat?). The windmill is going to get its kilowatt out of the air. But the power boat has to push it through the air, against that 1000n drag. Because of losses, you'll need *more* than a kilowatt of engine power to overcome the extra drag of the mill, but you'll only get a kilowatt, at best, out of the mill. Less than you put in. Remember that a stand-alone windmill cannot produce a forward force. It can only generate power that something else can make into a forward force. Are we there yet? Andy |
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There is a big difference between "does not exist" and "net force =
zero." "Bill" wrote: Yes there is. But how does one tell the difference? By pondering the difference between physics and semantics. If they were the same thing, we wouldn't need two different words for them, now would we? I'd like to be regraded. True. Very good, your average is improving. Please provide more details on your machine for using the Earth's rotation as a power source. Sounds like a great idea as long as we can keep it a secret from Al Gore. DSK |
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On 15 Oct, 19:17, Goofball_star_dot_etal
wrote: 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. To the windmill there is no difference between wind powered by the sun (in your terms true), or wind created by the diesel of the engine. (in your terms apparent). If I put a windmill in a 20kt wind and it makes 1kw, I can put the same windmill on a powerboat on a still day at 20kts and it will still make 1kw. Now if that 1kw is enough to push the windmill forward against the wind then that energy surplus will also exist for the windmill on the power boat so if you gear it to the prop shaft, after the drag of the windmill has been equalized, there will be some power left over to save some diesel. This is patently absurd so if you buy the idea the windmill boat/cart can drive forward into wind you have to explain this paradox away or explain how 20kts of wind created by diesel is different to 20kts of wind created by the sun. Anyway, I'm going to do what I did last time and ignore this thread. I'll revisit the thread in a few days time and if someone has posted the correct equations and worked it through with figures to show the windmill cart/boat can move directly into wind I shall post to acknowledge my acceptance that it is possible. Otherwise, I shall post nothing. |
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On 15 Oct, 20:11, "Graham Frankland"
wrote: "Ian" wrote in message ups.com... On 15 Oct, 14:19, (Richard Casady) wrote: Thrust from the engine, of course. My own aircraft has a take off mass of 370kg and no thrust whatsoever, and yet I can get it to go up. 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. Whether in a zoom or a thermal, I can get my glider to rise without smuch as a millinewon of thrust... 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. Nope. Lift is - by definition - always at right angles to the free stream air velocity. You might get the boat to go sideways a bit, but the assoiated drag will always slow you down as you do. Ian |
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On Mon, 15 Oct 2007 13:00:43 -0700, toad
wrote: On 15 Oct, 19:17, Goofball_star_dot_etal wrote: snipped some No it gets energy from a reduction of the kinetic energy of the _true_ wind. To the windmill there is no difference between wind powered by the sun (in your terms true), or wind created by the diesel of the engine. (in your terms apparent). ok. By "true" I assume no tide in this case. The frame of reference is the water and velocities are measured wrt to the water/land If I put a windmill in a 20kt wind and it makes 1kw, I can put the same windmill on a powerboat on a still day at 20kts and it will still make 1kw. ok. Now if that 1kw is enough to push the windmill forward against the wind then that energy surplus will also exist for the windmill on the power boat Just a minute.. (k) watts are units of power not energy. If you are to make sense of this you cannot mix your units and dimensions of force, energy, power, momentum etc. It might sound pedantic but it is absolutely fundamental that the dimensions on each side of an equasion match so if you gear it to the prop shaft, after the drag of the windmill has been equalized, there will be some power left over to save some diesel. This is patently absurd so if you buy the idea the windmill boat/cart can drive forward into wind you have to explain this paradox away or explain how 20kts of wind created by diesel is different to 20kts of wind created by the sun. Assuming no wind in this case, the affect of driving this windmill forward will be to increase the velocity of the air from zero to a finite value. In other words the kinetic energy of the air has increased, therefore you are doing work not extracting energy, at some rate. (same units:-) ) You must be losing power. Anyway, I'm going to do what I did last time and ignore this thread. ok, bugger off if you must.. I'll revisit the thread in a few days time and if someone has posted the correct equations and worked it through with figures to show the windmill cart/boat can move directly into wind I shall post to acknowledge my acceptance that it is possible. Otherwise, I shall post nothing. |
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toad wrote:
Anyway, I'm going to do what I did last time and ignore this thread. In case you don't, this needs a face to face discussion with drawings (and possibly beer!). Whereabouts are you? Andy |
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Bill wrote:
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. When do I need to change the battery? Change the battery when it runs down to the point that your photons & flashlight are only moving apart at about 90% of C grin. |
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On Mon, 15 Oct 2007 07:49:45 -0700, toad
wrote: 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. Of course not. It will continue to acquire kinetic energy at the same rate, so many foot pounds per second. It will mostly get heavier rather than going faster My 'calculator that takes no prisoners', [HP48] will do the calculations for E=MC^2. Without a calculation I will say that it would take a long time to double the mass, but there is no upper limit if you have the source of power. Casady |
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On Mon, 15 Oct 2007 07:55:38 -0700, Ian
wrote: On 15 Oct, 14:27, (Richard Casady) wrote: Why wouldn't it accellerate indefinitely with no friction anywhere in the system. Kelvin-Froude actuator disk theory is your friend. Not needed. The assumption of no friction, remember. The energy has to go somewhere. Do extremely simple arithmetic. Casady |
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On Mon, 15 Oct 2007 08:01:24 -0700, Ian
wrote: 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? Handwaving. The only possible source for the increase in the gravitational potential energy is the engines. Wings impart no energy that is not their function. There is drag that goes with lift, and engines have to impart energy to overcome it. I have had a commercial pilots license for more than forty years, if you want more handwaving. 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. Not in still air. You can get it to sink into a mass of rising air. Or do you have a balloon. Those burners suck fuel like an engine, the chief concern is having a source of energy same as with an engine. Casady |
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On Mon, 15 Oct 2007 17:34:01 GMT, You wrote:
Yep and I took a ride on a Steam Powered, Gear Driven, Railroad Train that operates out of Tillamook, Oregon, just two months ago... In 1988 the chinese were still producing steam locomotives. A tourist railroad in Boone Iowa has one of the last dozen produced at the Datong locomotive works. The did keep making parts for the ten thousand in service. Casady |
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On Mon, 15 Oct 2007 13:48:32 -0600, "Bill" wrote:
I have a scheme for tapping into the power of the rotating earth. I even built an apparatus that worked for several years. Michael Faraday built a small scale device working on the same principle. It is not perpertual motion or any crackpot scheme. It does slow down the rotation of the earth a little and causes local weather changes (on a very small scale). They already have these power stations that slow the earth's rotation. Its called harnessing tides. The rotating earth doesn't have power, it has stored energy, same as a charged battery that is just sitting there. Windmills cause weather change by subtracting wind speed. Casady |
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On 2007-10-15 11:14:20 -0400, "Bill" said:
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. How does one know it exists there? By measuring it? By using it. There are a few satellites sitting in the vicinity of the various Lagrange points. Even there, the gravitational forces aren't exactly cancelled, but exist in a dynamic balance. -- Jere Lull Tanzer 28 #4 out of Tolchester, MD Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/ Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/ |
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On Mon, 15 Oct 2007 13:43:24 -0600, "Bill" wrote:
oscillation velocity of a photon in a gravitational free fall even though its translational speed remains constant Does it not just get bluer falling in gravity. The higher the frequency, the more energy a photon has. Casady |
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On Mon, 15 Oct 2007 11:18:20 -0600, Paul Cassel
wrote: Yes, the steam would make the water move in many directions but the point is that it's not RUNNING uphill. It's being propelled uphill. True. However steam, water vapor is less dense than air and tends to rise, causing thunderstorms, where rising moist air can carry liquid water upward. The steam runs uphill, like a balloon, but the liquid water does not, it is carried. Casady |
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Jeannette wrote:
Stephen Trapani wrote: Putting wings on a plane increases aerodynamic drag acting on the plane, yet it increases the speed, right? Stephen I don't know that much but I think this statement is incorrect. Putting the wings on a plane does not increase the speed. It creates vertical lift which makes the plane go upward but it has to add to the drag and in fact slow the plane down. The reduced speed is of no concern to the plane as long as it doesn't slow it down enough to loose the lift. It can compensate for the loss of speed by putting more power anyway and getting more lift in the process which is what it is trying to do in the first place. As it goes further up it reaches thinner air which will cause less drag... In other words, one doesn't put wings on a plane to make it go faster but to make it go higher.. The wings take the plane off the ground into a different medium, reducing resistance, increasing the speed. Same thing happens with a hydrofoil. Stephen |
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You wrote:
In article , 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. Bingo. Getting it off the ground decreases resistance, increasing the speed. Same thing can happen with a boat. Stephen |
NORDHAVN Rewrites Physics Textbooks
Richard Casady wrote:
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. Getting the plane off the ground doesn't decrease it's resistance and increase it's speed? Stephen |
NORDHAVN Rewrites Physics Textbooks
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NORDHAVN Rewrites Physics Textbooks
"Richard Casady" wrote in message ... On Mon, 15 Oct 2007 13:43:24 -0600, "Bill" wrote: oscillation velocity of a photon in a gravitational free fall even though its translational speed remains constant Does it not just get bluer falling in gravity. The higher the frequency, the more energy a photon has. Casady http://antwrp.gsfc.nasa.gov/htmltest...lens_math.html "Photons climbing out of a gravitating object become less energetic. This loss of energy is known as a "redshifting", as photons in the visible spectrum would appear more red. Similarly, photons falling into a gravitational field become more energetic and exhibit a blueshifting. The observed energy E_observed at radius r_observed of a photon emitted at radius r_emitted with energy E_emitted is [7] " |
NORDHAVN Rewrites Physics Textbooks
"Bloody Horvath" wrote in message ... Uh... hot air rises. How can water vapor be less dense than air? You ****ing assholes have no idea of science. I'm Horvath and I approve of this post. http://en.wikipedia.org/wiki/Density_of_air "The addition of water vapor to air (making the air humid) reduces the density of the air, which may at first appear contrary to logic. This occurs because the molecular mass of water (18) is less than the molecular mass of air (around 29). For any gas, at a given temperature and pressure, the number of molecules present is constant for a particular volume. So when water molecules (vapor) are introduced to the air, the number of air molecules must reduce by the same number in a given volume, without the pressure or temperature increasing. Hence the mass per unit volume of the gas (its density) decreases." Who is the one lacking in science knowledge? |
NORDHAVN Rewrites Physics Textbooks
On 16 Oct, 00:11, (Richard Casady) wrote:
On Mon, 15 Oct 2007 08:01:24 -0700, Ian wrote: 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? Handwaving. The only possible source for the increase in the gravitational potential energy is the engines. Wings impart no energy that is not their function. There is drag that goes with lift, and engines have to impart energy to overcome it. I have had a commercial pilots license for more than forty years, if you want more handwaving. The question was not "where does the energy come from?". The question was "what force ... does work against gravity ...?" and (save for a trivially small downwards component) that ain't thrust. My own aircraft has a take off mass of 370kg and no thrust whatsoever, and yet I can get it to go up. Not in still air. A glider can climb in still air. Not for very long, normally, but it can certainly climb. No thrust. Or do you have a balloon. Those burners suck fuel like an engine, the chief concern is having a source of energy same as with an engine. How do you think helium balloons work? Ian |
NORDHAVN Rewrites Physics Textbooks
On 16 Oct, 00:00, (Richard Casady) wrote:
On Mon, 15 Oct 2007 07:55:38 -0700, Ian wrote: On 15 Oct, 14:27, (Richard Casady) wrote: Why wouldn't it accellerate indefinitely with no friction anywhere in the system. Kelvin-Froude actuator disk theory is your friend. Not needed. The assumption of no friction, remember. The energy has to go somewhere. Do extremely simple arithmetic. The momentum has to go somewhere consistently as well. "Simple" might work, but "simplistic" won't. Sorry. Ian |
NORDHAVN Rewrites Physics Textbooks
On Mon, 15 Oct 2007 18:00:19 -0700, Stephen Trapani
wrote: Getting the plane off the ground doesn't decrease it's resistance and increase it's speed? Unless the landing gear retract, there is not really that much difference. Casady |
NORDHAVN Rewrites Physics Textbooks
On Tue, 16 Oct 2007 01:13:56 -0700, Ian
wrote: How do you think helium balloons work? You have me there. However, how many do you think are in use? I would guess somewhere between zero and none. For all practical purposes they don't exist. Myself, I like to fly small hydrogen balloons. Dry cleaner bags. You dissolve aluminum chips in lye to get the hydrogen. Casady |
NORDHAVN Rewrites Physics Textbooks
On 16 Oct, 14:32, (Richard Casady) wrote:
On Tue, 16 Oct 2007 01:13:56 -0700, Ian wrote: How do you think helium balloons work? You have me there. However, how many do you think are in use? I would guess somewhere between zero and none. For all practical purposes they don't exist. Doesn't mean they don't work. Ian |
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