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Post by striker16 on Sept 13, 2012 8:18:19 GMT 1
Evidence for what, sorry? For anti-gravity properties of a spinning wheel.
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Post by mrsonde on Sept 13, 2012 8:49:17 GMT 1
Hmmm...yes, as Nay said, it's a shame this term comes so readily to mind. I'd point out that you're the only one on this thread who seems to have believed in such a force, literally. Laithwaite didn't, and I've been careful to put the phrase in quotes, or point out that the loss of weight is apparent. What there seems to be is a momentum of the wheel in an entirely unpredicted and unexplained direction - in this case at least contrary to the gravitational attraction of the Earth. As for the evidence for this, I refer you again to Laithwaite's demonstration.
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Post by striker16 on Sept 13, 2012 10:54:59 GMT 1
Hmmm...yes, as Nay said, it's a shame this term comes so readily to mind. I'd point out that you're the only one on this thread who seems to have believed in such a force, literally. Laithwaite didn't, and I've been careful to put the phrase in quotes, or point out that the loss of weight is apparent. What there seems to be is a momentum of the wheel in an entirely unpredicted and unexplained direction - in this case at least contrary to the gravitational attraction of the Earth. As for the evidence for this, I refer you again to Laithwaite's demonstration. I'm afraid we're just going around in circles because you seem to think this phenomenon has not been explained, but Newton's laws of motion covers this satisfactorily. If I was mathematically minded I would, no doubt, be able to offer a mathematical proof.
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Post by mrsonde on Sept 13, 2012 11:57:01 GMT 1
Hmmm...yes, as Nay said, it's a shame this term comes so readily to mind. I'd point out that you're the only one on this thread who seems to have believed in such a force, literally. Laithwaite didn't, and I've been careful to put the phrase in quotes, or point out that the loss of weight is apparent. What there seems to be is a momentum of the wheel in an entirely unpredicted and unexplained direction - in this case at least contrary to the gravitational attraction of the Earth. As for the evidence for this, I refer you again to Laithwaite's demonstration. I'm afraid we're just going around in circles because you seem to think this phenomenon has not been explained, but Newton's laws of motion covers this satisfactorily. As you are by your own description not mathematically minded, on what basis are you so confident that: Now, Laithwaite was about as mathematically minded as anyone you could hope to find, and was thoroughly familiar with Newton's laws. He evidently disagrees with you. All those physicists who disagreed with Laithwaite's obvious conclusion, that there is an unexplained force involved in this situation, were inexplicably as unable (or for some reason unwilling) as yourself to offer said proof. No one has ever offered it. We are merely supposed to take your and their word for it then? It exists, but we can't be bothered to furnish it, you'll just have to believe us that we know what it is, and could easily give it if we felt like it? What sort of game is that? Not science, that's for sure, and not reasonable debate. Look, let's go through this step by step - you don't have to be particularly mathematically minded to understand and apply Newton's laws, and the angular momentum equations. The mathematics are straightforward - multiplying and adding vectors, that's all (and we can skip the adding part, because in this case the body concerned is a symmetrical wheel.) Comprehending what the vectors relate to is much more difficult, because we're dealing with very unfamiliar abstract concepts - angular momentum, rate of change, and torque. But that's not mathematics, that's the philosophical meaning of the mathematics. Now - the angular momentum equation states that in Laithwaite's demonstration there is an angular momentum in the direction of the shaft of the wheel. It has to be in that direction - it's the product of the vector of the linear motion of all the particles in the wheel by the vector between, in the case we're trying to calculate, Laithwaite's hand. That's what the equation says. It's pointing horizontally in this experiment; in a situation of a spinning top, it's pointing upwards. Alright? But this is not a force, as you seemed to suppose earlier - it's a vector. A direction of motion persisting, in the absence of friction, indefinitely (according to Newton first law.) Now, Laithwaite moves the wheel. Now this does produce a force - a rate of change of momentum (Newton's definition of force, according to his second law.) This produces a torque, as the angular momentum vector changes in relation to the fixed direction of the external force, the direction of Earth's gravitational attraction. The vector of the torque is simply given by the equation and Fleming's rule by the product of the vectors of gravity, F, and in this case of the shaft, r - it must, whatever the angle of the shaft, be at right-angles to it, that is, parallel to the wheel; and it must be at right-angles to F - that is, in a horizontal plane. The torque is in the direction of Laithwaite's circular motion. Or, in the case of a spinning top, its axis tilted, in the directionof its precession, round and round, at right-angles to the force of gravity. Nowhere in this description is there an upward force described by the angular momentum equation. Well, that's not absolutely perfectly utterly accurate - there is another torque produced, as Laithwaite turns, and alters the angle of the wheel: but this upward torque is exactly equalled by a downward torque, on the obverse face of the wheel, so it's cancelled out. And that's it - that's all Newton's laws say, that's all the angular momentum equations derived from them describe. No upward force. No change in mass. No change in the force of gravity: no change in weight. How and why is Laithwaite able to effortlessly lift 40 and more pounds over his head, therefore? I can't put it any simpler than that. If you disagree, the onus is on you to find a step in the equations I've somehow neglected - or, if that's too mathematical, find a descriptive text explaining what that step might be (as I said earlier, this is basic classical physics - it should be in every A-level textbook.)
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Post by striker16 on Sept 13, 2012 15:24:07 GMT 1
Nobody is saying there is an upward force - this is completely missing the point. A spinning wheel, or whatever, produces angular momentum which seeks to maintain that angular momentum, whatever position the wheel is oriented in. This is why a gyro, for example, can be placed parallel to the surface of the earth - because it tries to maintain its axis regardless of its position relative to the earth. Yes, it is easy enough to move a spinning wheel by hand (as Braithwaite did in his demo.) but this is a result of an additional force supplied by him and which is made easier to use due to the fact that gravity is being opposed, which is in accordance with Newton's principle that an object in motion will continue to be in motion unless acted upon by some other force. I do not know why you are going on about vectors and torque because they are both properties of force, something you seem to want to dispense with.
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Post by striker16 on Sept 13, 2012 15:37:30 GMT 1
How and why is Laithwaite able to effortlessly lift 40 and more pounds over his head, therefore? He is not having to lift 40 pounds because the spinning wheel is opposing the pull of gravity and, therefore, largely cancelling it out. All Braithwaite was doing was providing a modest additional force in order to change the wheel's axial rotation. Again, you seem to be confusing the efect of angular momentum with upward 'lift.' A spinning wheel cannot fly, but what it can do is maintain its orientation in space, which is very useful for navigational purposes. It seems to me you have convinced yourself about some ideas about spinning wheels and gyroscopes that are just not correct. Sorry.
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Post by mrsonde on Sept 13, 2012 16:13:50 GMT 1
Nobody is saying there is an upward force - this is completely missing the point. A spinning wheel, or whatever, produces angular momentum which seeks to maintain that angular momentum, whatever position the wheel is oriented in. This is why a gyro, for example, can be placed parallel to the surface of the earth - because it tries to maintain its axis regardless of its position relative to the earth. Yes, it is easy enough to move a spinning wheel by hand (as Braithwaite did in his demo.) but this is a result of an additional force supplied by him and which is made easier to use due to the fact that gravity is being opposed Unobjectionable up to the point of the last sentence. By what is gravity being opposed? There's a vector sideways, due to the torque, not upwards. This turns him in a circle: it doesn't make the weight any the less. And the force acting in opposition to gravity is? There are only two forces involved here. The change in the angular momentum vector as Laithwaite alters the angle of the wheel's axis, producing the torque sideways. And gravity. There is no other force mentioned in Newton's laws, or the angular momentum equation. Given that, you need to explain where this upward momentum, giving the phenomenal impression of a loss of weight, is coming from. It's not given by Newton's laws - unless you know something about them that no other physicist has yet been able to come out with? I'm all agog.
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Post by mrsonde on Sept 13, 2012 16:23:51 GMT 1
How and why is Laithwaite able to effortlessly lift 40 and more pounds over his head, therefore? He is not having to lift 40 pounds because the spinning wheel is opposing the pull of gravity I keep asking you: how is it? Not according to Newton's mechanics and the angular momentum equations it's not. If you think it is, kindly explain why - where is this opposition coming from? The angular momentum is sideways, in the direction of the shaft - no force there, as Laithwaite points out: no pull on his arm. The torque produced by the change in the angular momentum vector is sideways, in a horizontal circle, just as happens when you tilt a spinning top. No momentum upwards, just as the spinning top doesn't start to rise from the floor. Nonsense. The two vectors of the only forces involved - the only ones mentioned by Newton's mechanics, at any rate - are multiplied together, not subtracted. Thus the natural unassisted trajectory is in a circular curve downwards, towards the Earth: not upwards. Producing a torque sideways, at right-angles to the vector of gravity, not against it. Look at the equation. And how in this situation does that assist in any respect it being lifted into the air? Well, correct me then. So far you've merely stated the obvious, and said nothing of any relevance to its apparent loss of weight. The issue is very simple - where is the momentum in opposition to gravity coming from?
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Post by striker16 on Sept 13, 2012 16:53:58 GMT 1
If the wheel stopped spinning it would simply fall over, so how is there not a force opposing gravity when it is spinning? Are you trying to say the spinning wheel is able to defy gravity using some kind of electrical power? But, again, nothing is losing weight. Does a discus lose weight when spun around by a discus thrower? No, and when the thrower releases the discus it transfers its angular momentum to linear momentum, and eventually drops to the ground through the pull of gravity, returning to its rest state, having spent the force imparted to it by the thrower. This is simple enough, isn't it? Newton was right.
I'm sorry, but you seem to be misinterpreting the technical terms so much that you are missing the bigger picture. It seems to me you have a conclusion-led opinion and are distorting the science in support of it. Perhaps you cannot see the wood for the trees!
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Post by mak2 on Sept 13, 2012 17:34:34 GMT 1
Prof. Laithwaite evidently had a sense of humour! To put his "feat" into perspective. In the 2004 Olympics, Hossein Rezazadeh lifted 263 Kg. We should not be surprised that Laithwaite could raise 40 lbs. ( about 20Kg ) even with one arm. The difficult part of a lift is the transition from pulling up to pushing up. I think that the professor used the gyroscopic effect of the rotor to help with this.
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Post by striker16 on Sept 14, 2012 9:44:05 GMT 1
Prof. Laithwaite evidently had a sense of humour! To put his "feat" into perspective. In the 2004 Olympics, Hossein Rezazadeh lifted 263 Kg. We should not be surprised that Laithwaite could raise 40 lbs. ( about 20Kg ) even with one arm. The difficult part of a lift is the transition from pulling up to pushing up. I think that the professor used the gyroscopic effect of the rotor to help with this. I'm trying to work out what mrsonde thinks is causing a spinning wheel to behave as it does other than by the energy imparted to it by causing it to spin. All the effects involved, such as angular momentum, precession and torque are merely an interplay of mechanical forces, so where is the big mystery?
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Post by Progenitor A on Sept 14, 2012 10:35:45 GMT 1
Prof. Laithwaite evidently had a sense of humour! To put his "feat" into perspective. In the 2004 Olympics, Hossein Rezazadeh lifted 263 Kg. We should not be surprised that Laithwaite could raise 40 lbs. ( about 20Kg ) even with one arm. The difficult part of a lift is the transition from pulling up to pushing up. I think that the professor used the gyroscopic effect of the rotor to help with this. I'm trying to work out what mrsonde thinks is causing a spinning wheel to behave as it does other than by the energy imparted to it by causing it to spin. All the effects involved, such as angular momentum, precession and torque are merely an interplay of mechanical forces, so where is the big mystery? Ah! I am glad that we have a member who does not regard it as a mystery! Perhaps you can explain how this unmysterious force actually operates to oppose gravity, and whether , when the spin is reversed the force AIDS gravity, and if , when the spinning disc spin is at right angles to the gravitational field, whether the disc will move to the right or left and how that is depnedant upon the direction of spin?
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Post by striker16 on Sept 14, 2012 11:32:29 GMT 1
I'm trying to work out what mrsonde thinks is causing a spinning wheel to behave as it does other than by the energy imparted to it by causing it to spin. All the effects involved, such as angular momentum, precession and torque are merely an interplay of mechanical forces, so where is the big mystery? Ah! I am glad that we have a member who does not regard it as a mystery! Perhaps you can explain how this unmysterious force actually operates to oppose gravity, and whether , when the spin is reversed the force AIDS gravity, and if , when the spinning disc spin is at right angles to the gravitational field, whether the disc will move to the right or left and how that is depnedant upon the direction of spin? I have to make it clear that I have no formal qualifications in physics, so I am merely offering my opinion based on the small amount of research I have on this subject, but having stated that, it seems clear to me that regarding the finer points of this phenomenon, the effects are all a result of the interrelationship of the mechanical forces generated by the spin imparted to the wheel. It's probably important to bear in mind we are not so much dealing with individual objects here in terms of a wheel, a piece of string, etc., but essentially of forces. This is why many people are amazed when they first come across the affects of gyros - they seem to defy intuition, but when we view what goes on as a combination of forces - not as a wheel seemingly able to levitate by magic- it becomes easier to grasp. To properly answer your queries about this phenomenon requires a mathematical discussion because words alone do not provide the rigour you are seeking which, I'm afraid, is beyond the scope of my abilities. We need a qualified person to make things clearer. "Despite this rejection and despite the fact that Laithwaite later acknowledged that gyroscopes behave fully in accord with Newtonian mechanics, he continued to explore gyroscopic behaviour, maintaining the belief that some form of reactionless propulsion could be derived from them." en.wikipedia.org/wiki/Eric_Laithwaite#BiographyDoesn't this show that Laithwaite was so taken away with his own ideas he rather lost touch with reality? If reactionless propulsion was a reality don't you think we would have seen it applied by now?
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Post by Progenitor A on Sept 14, 2012 13:24:49 GMT 1
I have to make it clear that I have no formal qualifications in physics, so I am merely offering my opinion based on the small amount of research I have on this subject, but having stated that, it seems clear to me that regarding the finer points of this phenomenon, the effects are all a result of the interrelationship of the mechanical forces generated by the spin imparted to the wheel. It's probably important to bear in mind we are not so much dealing with individual objects here in terms of a wheel, a piece of string, etc., but essentially of forces. This is why many people are amazed when they first come across the affects of gyros - they seem to defy intuition, but when we view what goes on as a combination of forces - not as a wheel seemingly able to levitate by magic- it becomes easier to grasp. To properly answer your queries about this phenomenon requires a mathematical discussion because words alone do not provide the rigour you are seeking which, I'm afraid, is beyond the scope of my abilities. We need a qualified person to make things clearer. That's a shame, the mystery remains. If the force is reversed when the spin is reversed then there is, I think, no mystery, if it does not the mystery remains en.wikipedia.org/wiki/Eric_Laithwaite#BiographyDoesn't this show that Laithwaite was so taken away with his own ideas he rather lost touch with reality? If reactionless propulsion was a reality don't you think we would have seen it applied by now? Don't think so - not for as long as there is a mystery for the direction of this Newtonian force
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Post by speakertoanimals on Sept 17, 2012 0:19:22 GMT 1
"In plain English, the 'turning point' is where it is neither going up nor going down and that is the point of zero weight."
Wrong. The gravitational force acting on the thrown stone is the SAME at any point of its trajectory. Ditto its acceleration. All that happens at the top of its trajectory is that the instantaneous velocity is changing from being upward to being downward. At that instant, v=0, but its acceleration (dv/dt) has the same value it has throughout the whole of the trajectory.
As regards weight, if you were sealed inside a thrown cannonball, you'd FEEL weightless throughout the whole of the flight, since you and the ball surrounding you are both free-falling in earths gravitational field, whether you are travelling upwards or downwards.
If people can't understand the basics of velocity and acceleration for simple situations, no wonder their folk-physics goes awry when trying to deal with gyroscopes...................
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