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Post by marchesarosa on Sept 9, 2012 8:50:15 GMT 1
In thinking about the spin of Laithwaite's weight relative to the spin of the Earth I realise that the spin of the weight is not necessarily at right angles to that of the Earth as I stated. It would depend upon where on the Earth you were standing, as Mr Sonde hinted at in his question about whether the effect would be identical in the other hemisphere.
I would want to know whether the effect would be different at the Equator, where the spin of the weight (when airborne) would be in the same plane as that of the Earth, from that at the Poles where the spin would be at right angles to the Earth's. And what would happen if the spin imparted by the electric drill was in the opposite direction to the spin of the Earth?
Am I getting warm?
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Post by Progenitor A on Sept 9, 2012 10:05:09 GMT 1
Yes, but it is a Global Phenomenon, nothing to worry about personally
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Post by marchesarosa on Sept 9, 2012 19:00:06 GMT 1
Touché, nay!
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Post by mrsonde on Sept 10, 2012 3:02:04 GMT 1
Rapidly spinning pieces of metal like lathes, for example, are usually anchored firmly to a very large lumps of concrete so they do not fly off into the air and injure people. True. But a spinning lathe would not be expected to fly off upwards into the air, would it? It might bounce off something and be expected to do so, as a classical action-reaction. Yes, I'd say so. I'm not all that familiar with discuses, on the other hand; but my first instinct is to think you're misdescribing its behaviour. Again, I wouldn't think this is a correct description. The centre of gravity of a spinning plate is carefully positioned directly above the rod - it's not weightless. And I'd say that at no point is a discus not being pulled downwards on a downwards ballistic path by the constant force of gravity. Yes, good idea. This is a very unusual circumstance, however: I can't think of any parallel examples. I'm sure you know Newton's Laws of Motion. O-Level fodder. The angular momentum equations derived from them are more exotic and unfamiliar, and I suggest even the people who think they understand them are somewhat kidding themselves. It's a very unfamiliar phenomenon, altogether. I once had a long argument over dinner and into the night with a Cambridge PhD Physics wizzkid who was insistent that there was no such phenomenon as orbital resonance in the solar system - no mention of it in the mathematics, Newtonian or Relativistic, you see. Therefore it couldn't exist. (This was before the close-up measurements of Saturn's rings, and he'd never come across the Mars-Jupiter or Uranus-Pluto or any of the other fairly well-known resonances between the planets.) Wouldn't they fly off into the ground first? Yes, broadly. At least, there is no phenomenal difference - you remember the hostesses walking around the rim of the spinning space station in 2001: A Space Odyssey? I think I feel fairly confident in saying that's not the right explanation, Marchesa, though a valiant effort. That much at least I'm certain is not covered by Newton. No obtuseness. Or if there is I share in it.
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Post by mrsonde on Sept 10, 2012 3:19:32 GMT 1
Surely, if this was a correct scientific principle, a practical working anti-gravity model would have been made and tested, which is why I'm a bit suspicious about the legitimacy of this idea. Perhaps the energy required to make this technology a practical reality is simply far too great? What is the principle you're referring to, Striker? Laithewaite certainly never said there was an anti-gravity principle evidenced here. He claimed rather that there was an interplay of forces occurring that was not covered by Newton's (or anyone else's) laws of motion. Most of his working life was concerned with inventing devices that apparently counteracted gravity - the MagLev, the Magnetic River, and so on. There's a nice demo of the latter here: If he'd thought for a minute this indicated a principle of anti-gravity, he'd have said so. Rather - it's a mystery. There's a momentum upwards in this situation (anti-gravity, if you like, metaphorically) that is not predicted, that was his argument.
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Post by mrsonde on Sept 10, 2012 3:22:48 GMT 1
I don't mean in the demo just posted above. (Though aluminium is not ferromagnetic, if you were thinking that was entirely to be expected!)
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Post by mrsonde on Sept 10, 2012 3:29:39 GMT 1
In thinking about the spin of Laithwaite's weight relative to the spin of the Earth I realise that the spin of the weight is not necessarily at right angles to that of the Earth as I stated. It would depend upon where on the Earth you were standing, as Mr Sonde hinted at in his question about whether the effect would be identical in the other hemisphere. I would want to know whether the effect would be different at the Equator, where the spin of the weight (when airborne) would be in the same plane as that of the Earth, from that at the Poles where the spin would be at right angles to the Earth's. And what would happen if the spin imparted by the electric drill was in the opposite direction to the spin of the Earth? Am I getting warm? Yeah, I might see you later after all. There's no solution to this puzzle, Marchesa - well, most physicists claim Newton gave it, but they decline to explain how to mere mortals like Laithewaite or us. What would happen to the weight of the spinning wheel if the shaft extended through the other side and was held by another person, like a bicycle wheel? Would they together find it equally as easy to lift it above their heads? Probably not, is my intuition - which would suggest the solution lies in something to do with the torque.
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Post by mrsonde on Sept 10, 2012 3:33:00 GMT 1
You're an engineer, Nay - what are your thoughts about this?
Hmmm. A worrying development.
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Post by striker16 on Sept 10, 2012 9:52:09 GMT 1
Gravity itself is defined as a force that is the result of the distortion of space due to the presence of matter, or mass, so with a rapidly spinning wheel do we not have the same principle operating where the the effect of spinning creates a slight distortion in space, thereby counteracting to some extent the earth's gravity? Or, perhaps, such an effect is so minuscule that it can be discounted, I'm no physicist so I don't know. I think it probably has more to do with centrifugal force as, for example, was seen in the movie: 2001: A Space Odyssey. The fastly spinning wheel creates a force that is opposed to the gravitational field of the earth, thus making it light to hold. Ordinarily, a rocket escapes the earth's gravity by producing sufficient thrust to reach an escape velocity but, of course, in that case the rocket travels away from the earth, however, with a spinning wheel, the 'thrust' of the wheel is trapped in a circular motion so the wheel never moves anywhere, nevertheless, it does oppose the pull of the earth, allowing it to be much lighter than normal.
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Post by striker16 on Sept 10, 2012 15:47:08 GMT 1
Apparently, this effect is due to the angular momentum of the wheel, I've now learnt, which resists any changes to its rotational axis and is the same effect one sees in a missile which tends to follow the same path unless acted upon by another force. Gyroscopes use this idea in maintaining their orientation in navigational aides. You could even place a spinning gyroscope parallel to the earth's surface sitting on a piece of string and it would want to stay there as long as its spin lasted. So, nothing magical, I'm afraid, just one of Newton's Laws of Motion.
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Post by mrsonde on Sept 10, 2012 16:40:19 GMT 1
Gravity itself is defined as a force that is the result of the distortion of space due to the presence of matter, or mass, so with a rapidly spinning wheel do we not have the same principle operating where the the effect of spinning creates a slight distortion in space, thereby counteracting to some extent the earth's gravity? You're getting all relativistic on me again! Yes, you're right, I think - as I said, angular momentum is one of those everyday phenomena that physicists and people in general assume is fully understood, but once you start looking closely raises more questions than the consensual understanding answers. Like clouds for example, or water droplets generally, or colours, or money. Accelarated motion is equivalent to a gravitational field, by any phenomenal experiment we might conduct. Curvilinear motion is acceleration. As such one would expect it to be indistinguishable from a gravitational field - viz Kubrick's space hostess. But only internally, I think - from the outside, the total mass hasn't changed, the space-time curvature is internal, so there should be no effect on its gravitational attraction to external objects...I think. If on the other hand you're right, and there is a counteraction to the gravitational field overall, then all the calculations leading to the dark matter hypothesis are simply wrong. Which we know anyway, from later observations. There's something wrong with the angular momentum equations - which was Laithwaite's original contention. 2,500 rpm isn't a very great speed, cosmically speaking. And the effect is clearly quite significant - Laithwaite taught Prince Charles to do this with a 50 lb weight in less than five minutes. This is someone who doesn't even know how to squeeze his own toothpaste. But that force is equally distributed around the wheel - as much reinforcing the gravitational attraction of the Earth as counteracting it. And it's purely an internal force, acting on the particles of the wheel. It shouldn't make any difference to the weight experienced by someone lifting it. I think. ;D How does it oppose the pull of the Earth? ;D
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Post by mrsonde on Sept 10, 2012 16:49:13 GMT 1
Apparently, this effect is due to the angular momentum of the wheel, I've now learnt, which resists any changes to its rotational axis and is the same effect one sees in a missile which tends to follow the same path unless acted upon by another force. Gyroscopes use this idea in maintaining their orientation in navigational aides. You could even place a spinning gyroscope parallel to the earth's surface sitting on a piece of string and it would want to stay there as long as its spin lasted. So, nothing magical, I'm afraid, just one of Newton's Laws of Motion. This is the standard riposte. You don't think Laithwaite was fully aware of Newton's Laws of Motion, and the principles of angular momentum? I remind you, "this effect" far from being clearly understood according to 300 year old classical equations, had never before been remarked upon before Laithwaite's demonstration of it. Because it was insignificant, unremarkable, unimportant? I don't think so. Gyroscopes are well understood. How does the resistance to any change in its rotational axis translate to an apparent reduction in weight? You experience a torque, and fighting the torque requires effort, but how does following the momentum of the torque reduce weight?
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Post by mrsonde on Sept 10, 2012 16:52:11 GMT 1
What I mean is: changing the axis of a gyroscope requires effort, yes: but not doing so does not result in it being easier to lift. It doesn't change its weight.
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Post by Progenitor A on Sept 10, 2012 17:02:57 GMT 1
Hi Nick Yes I was an engineer and no, I do not have a clue about this phenomenon that Laithwaite demonstrated That there is an 'anti-gravity' force at work is undoubted - pity he called it that as it invokes mad images of science fiction and Dan Dare. But an ant-gravity force is simply some force that acts against gravity, and we are all familiar with such forces
Where that force arises in a spinning wheel I do not know. I note that he demonstrates it where the spin is in the same (vertical) plane as the gravitational field. What happens to the force when the spin is at right angles to the gravitational field , which way does the force act then? It should ( think) cause the disc to move either to the right or left. If it does neither then it is indeed a mysterious force (even more mysterious than it is in the demonstration)
Also what happens to the force when the spn is reversed
Fascinating
I agree with you that the standard mathematical explanation is not good enough. The set up is so simple that it should be explicable in simple English
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Post by striker16 on Sept 10, 2012 17:04:57 GMT 1
Gyroscopes are well understood. How does the resistance to any change in its rotational axis translate to an apparent reduction in weight? You experience a torque, and fighting the torque requires effort, but how does following the momentum of the torque reduce weight? I don't think the wheel really loses weight. A stone thrown does not lose weight but due to the force imparted to it resists the pull of gravity until the force given to it runs out. It's just a question of opposing forces. Is this what you mean?
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