Naked Science Forum
Non Life Sciences => Physics, Astronomy & Cosmology => Topic started by: cheeeezy on 26/01/2021 13:21:11
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Some time ago it occurred to me that Eric Laithwaite might have a point in asking everyone to reexamine the "scientific" explanations of the Gyroscopic Effect. All they were saying was that Newtons laws insisted that Conservation of Momentum had to apply to the angular momentum build up in a rotating solid. Of course, anyone whos ever played with a Gyroscope has observed the equal and opposite force law gets thrown under that bus. Simply applying Occam's Razor to this anomaly led me to a much more reasonable explanation. The basic principle that a solid is a form of matter where the electron orbitals are locked together, led me to a simple obvious conclusion. Since almost all the weight of an atom is in the nucleus, wouldn't spinning a solid cause the nuclei to be thrown outward due to centrifugal force? And wouldn't the shifting outward of the nuclei inside the electron shells cause an electromagnetic imbalance in each atom? As I experimented with various flywheels it became obvious that the tangential force was simply answering to the electronic righthand rule. The nuclei were simply "unwinding" due to the mechanical force applied to them. BTW, if the "light" goes on for some one else, I've already got the patent :)
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Have you spun up any flywheels while sitting in a chair that is free to rotate? You may find that "equal and opposite" (conservation of angular momentum) still applies here.
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Eric Laithwaite was a hell of a nice guy but sadly didn't understand Newtonian physics. Scientific laws don't "insist" , they describe. And they describe everything we know about gyroscopes even to the point that you can make quantum mechanical predictions from them despite the fact that electrons don't actually orbit the nucleus.
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And I have patented dozens of chemical compounds that have never been made (some of which I know cannot be stable, but they're still mine, all mine!) The fact that they are patented doesn't mean that these compounds are "real."
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Of course, anyone whos ever played with a Gyroscope has observed the equal and opposite force law gets thrown under that bus.
In what way?
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What is this "tangential force" you speak of?
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I already said: Right Hand Rule = 90degrees
You may well have said that, but it is meaningless.
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spin up a flywheel and try to push it sideways - voila!
And it moves in exactly the way that physics says it should.
That's my point.
The laws of physics work just fine for gyroscopes.
So this
Of course, anyone whos ever played with a Gyroscope has observed the equal and opposite force law gets thrown under that bus.
is nonsense
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The "gyroscopic" effect seems difficult to explain. Like how it's difficult to explain bicycles.
I mean, if you get onto a bicycle when it's stationary, you immediately fall over. But if you pedal it forwards, and gain a bit of momentum, you don't fall over. I've seen various explanations of why that is.
Some of the explanations invoke a "gyroscopic" effect. Other explanations dismiss that, and appeal to continuous "micro-muscular" movements by the bicycle rider, to maintain a balanced, upright posture.
It's all a bit mysterious.
Is there some key insight awaiting discovery, that might transform our understanding of physics?
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Yes the laws of physics, not newtons "rule" of equal and opposite reactions.
That is one of the laws and yes, it's obeyed.
I'll leave how it does it to whomever wants to figure it out.
They figured it out a hundred and odd years ago.
https://en.wikipedia.org/wiki/Vector_calculus#:~:text=Vector%20calculus%20was%20developed%20from,their%201901%20book%2C%20Vector%20Analysis.
You could learn it. I'm REALLY tired of beating a brick wall....
Well, why did you turn up here?
Surely you knew that posting nonsense wasn't going to get very far.I'm simply trying to explain the fact that the force that causes the gyroscopic effect is a nuclear reaction,
That's not a fact. If you try to pretend it is then you will be banging your head against the wall again.
Why not stop and learn some science instead?
It's going to be more rewarding.
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Some of the explanations invoke a "gyroscopic" effect.
And they are wrong- as has been shown by experiment.
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Some of the explanations invoke a "gyroscopic" effect.
And they are wrong- as has been shown by experiment.
Yes, but I remember reading, until quite recently, that moving bicycles stay upright because of the gyroscopic effect created by the whirling wheels.
That was the orthodox theory. Now disproved, or so you claim.
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(At the risk of getting Alan involved...)
If you look at just about any textbook that tells you how planes fly, it will give an answer that isn't just false, but obviously false. There's usually some nonsense about the Bernoulli effect and the air having to travel faster over the top of the wing because of the shape (in cross section) of the wing.
Which is fine, until you remember that you can fly a stunt plane upside down indefinitely...
Just because an explanation is common, doesn't make it right.
It turns out that what keeps a bike upright is... the rider.
https://www.cam.ac.uk/research/discussion/opinion-how-does-a-bike-stay-upright-surprisingly-its-all-in-the-mind
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Here is a simple example of the gyroscope effect.
You have a rotating object with 2 spherical masses on the end of rods and attached to central axis shaft.
The arrows indicate which direction each of the masses' momentum is carrying at a given moment. From this view, one is going up and the other down.
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Now you grab the axial shaft and suddenly rotate it 90 degrees along the axis joining the sphere.
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The spheres themselves are not displaced but neither is the direction of their momenta changed, which remains in an up and down direction. This is transferred to the axial shaft via the connecting rods, will will try to twist the shaft perpendicular to its own axis. To you, it will feel like the shaft is trying to rotate 90 degrees to the direction you are trying to rotate it.
If you expand this to a spinning disk, you always have some parts of it which have a momentum that will fight you if you try to change the axis of rotation.
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(At the risk of getting Alan involved...)
If you look at just about any textbook that tells you how planes fly, it will give an answer that isn't just false, but obviously false. There's usually some nonsense about the Bernoulli effect and the air having to travel faster over the top of the wing because of the shape (in cross section) of the wing.
Which is fine, until you remember that you can fly a stunt plane upside down indefinitely...
Just because an explanation is common, doesn't make it right.
It turns out that what keeps a bike upright is... the rider.
https://www.cam.ac.uk/research/discussion/opinion-how-does-a-bike-stay-upright-surprisingly-its-all-in-the-mind
Excellent post BC. As always. :
About the Bernoulli effect. Agree with you completely. I never believed that was why aeroplanes fly. I remember reading, years ago, a book by Len Deighton, which contained a diagram captioned: "The Secret of Flight".
The diagram was of a wing aerofoil section - you know what I mean - under-surface flat, upper-surface curved.
I knew that was bollards. In my youth I built model aeroplanes with wings of flat balsa wood. Completely flat, top and bottom. No trace of aerofoil. Yet my planes flew very well. I could go on about this. But it would be too boring!
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That force is created by unwinding the nucleons, and thereby best described as "cold fission".
Have you tried making a gyroscope out of uranium or thorium, and tested whether the radiation level increases when you increase the spin? (eg using a Geiger counter)
- Have you tried to test for new elements created by cold fission?
- Have you used a gyroscope made out of more conventional materials like iron or aluminium, and seen cold fission occur? Where would the energy come from? (It consumes energy to split the nucleus of elements iron and lighter.)
One of the more common ways of refining uranium is to put it in a centrifuge, made out of the strongest known alloys, and spin it at the highest possible speed. If a gyroscopic effect produced fission, it would have been noticed!
https://en.wikipedia.org/wiki/Gas_centrifuge#Separating_uranium-235_from_uranium-238
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I'm simply trying to explain the fact that the force that causes the gyroscopic effect is a nuclear reaction,
Quite a lot of gyroscopes are made mainly from iron. Iron(well, at least one of the isotopes) is near the bottom of the nuclear binding energy curve.
The nuclei are too heavy for fusion to work, and too light for fission to work.
What nuclear reaction is possible?
Also, the world has been spinning for billions of years, why hasn't it finished reacting yet?
Why is there no evidence of products of reaction?
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there are two ways to release nuclear energy: 1- blowing up nuclei (stupid way) 2- unwinding the nuclei through a method that requires intelligent thought Too bad people keep choosing a path toward self destruction :(
Klatu Barada Nicto
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there are two ways to release nuclear energy: 1- blowing up nuclei (stupid way) 2- unwinding the nuclei through a method that requires intelligent thought Too bad people keep choosing a path toward self destruction :(
Klatu Barada Nicto
Do you understand that this is a science page?
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Yes, but I remember reading, until quite recently, that moving bicycles stay upright because of the gyroscopic effect created by the whirling wheels.
That was the orthodox theory. Now disproved, or so you claim.
It never appeared in any physics textbooks that I read. Bicycle wheels are designed to have the minimum moment of inertia consistent with their intended load and terrain. If you try to turn a heavy, spinning wheel, say to the left, it will try to flip you over to the right - not what we want on a bike!
Bicycle stability arises from the angle of the front tube. If you lean slightly to the left, the wheel turns to the left, so the bike starts to turn left and centrifugal force stops the bike from falling over. You can demonstrate this by making a bike with zero or negative tube angle, the latter being pretty impossible to ride.
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Which is fine, until you remember that you can fly a stunt plane upside down indefinitely...
Only if it has a symmetrical wing cross section or you are prepared to add a lot more thrust (engine power) than right way up.
You can measure the Bernouilli lift in a wind tunnel, or realise that it is the same phenomenon as the venturi suction that makes the carburettor ice up and stop the engine working when you are having a bad day (yes, sadly, we still use carburettors in lots of small planes.)
There are lots of compromises in wing design, but nobody would go to the trouble of making the cross section asymmetric for slow flight, if it didn't provide more lift than a symmetric wing.
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It turns out that what keeps a bike upright is... the rider.
Funny, that. You can get off and push the bike away from you, and it stays upright for quite a while with nobody on it!
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It turns out that what keeps a bike upright is... the rider.
Funny, that. You can get off and push the bike away from you, and it stays upright for quite a while with nobody on it!
Funny that- you take the big heavy weight off the top and it becomes more stable.
"for quite a while"
Not nearly as long as it stays upright when the rider is on it.
What was your point?
you are prepared to add a lot more thrust
They are.
And, in those circumstances the "classic" explanation of how planes fly should lead to the plane power-diving into the ground.
But the plane doesn't do that.
And that's because the "theory" is, at best, not the whole story.
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But the plane doesn't do that.
because the key element that determines lift, for all aerofoils, is the angle of attack - the angle between the wing chord and the direction of travel. It's all in the textbooks, and if you use an inverted aerofoil with a negative AoA it does indeed produce downthrust. But don't tell the people who design cars, who think it's entirely due to magic.
The art of inverted flight is to maintain the appropriate AoA . The more symmetrical the aerofoil, and the smaller the angle of incidence (the angle between the wing chord and the fuselage reference line) the easier this is, because your horizon reference changes less. You can find plenty of images of planes like the Extra or Pitts, which are designed for sustained inverted flight, compared with say a Cessna 172, with a high-lift (very asymmetric) wing and no taste for such silliness.
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Not nearly as long as it stays upright when the rider is on it.
So we put a big heavy weight on the bike (i.e. a rider) and it stays upright? It's remarkably difficult to keep a bike upright when it's stationary, but no problem when it's moving quickly, and you can steer it by leaning, hands off, which rather suggests an inbuilt dynamic mechanism. Big motorbikes weigh a lot more than the rider, who can't shift very much, but they also stay upright, and have angled front forks. One wonders why.
I thought you had spent your best years in Oxford - hasn't bicycle technology reached the midlands yet?
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It's remarkably difficult to keep a bike upright when it's stationary
That's because you fall over sideways, but you can't easily move a stationary bike sideways to compensate.
hasn't bicycle technology reached the midlands yet?
Oxford was awash with bikes when I was there- about 35 years ago- and I imagine it still is.
But it's not the technology that we are addressing, it's the understanding. People rode also horses before they had any meaningful understanding of how a horse worked.
So we put a big heavy weight on the bike (i.e. a rider) and it stays upright?
Yes, though, if the big heavy weight stops actively controlling the system, they fall over.
That pretty much nails the point.
What keeps it upright is careful direct control by the user.
You pretty much say so yourself...
you can steer it by leaning
It is clearly you that does the control,.
In any event, it can't be the gyroscope effect.
People have made bikes with contrarotating wheels to cancel that out, and they are still rideable.
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because the key element that determines lift, for all aerofoils, is the angle of attack
I know that.
You know that.
It's more or less my point.
The textbooks all bang on about Bernoulli, but it's the "pushing the air down" that actually keeps you up.
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So we put a big heavy weight on the bike (i.e. a rider) and it stays upright?
Yes, though, if the big heavy weight stops actively controlling the system, they fall over.
That pretty much nails the point.
What keeps it upright is careful direct control by the user.
Alan is right. A bicycle (with or without this heavy brick on the seat) will stay upright as long as it maintains enough speed to do so, which is indefinitely in a frictionless environment. A bicycle is designed to not fall over on its own while at speed. It is the angle of the fork and the offset (the fork is curved, not straight) which does this.
You pretty much say so yourself...
you can steer it by leaning
It is clearly you that does the control,.
It is you that can choose where the bike steers, something the heavy brick isn't going to do. But it's not you that keeps it upright. You can fall asleep on a bike and assuming you're sufficiently strapped to it, it doesn't fall over.
In any event, it can't be the gyroscope effect.
No, I agree it's not that.
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bicycle (with or without this heavy brick on the seat) will stay upright as long as it maintains enough speed to do so,
It is a relief to know that bike crashes can't happen and that any toddler can ride a bike because all they need to do is provide motive power.
No need for any complex controls, so obviously the people who build cycling robots are fraudsters, and the crashes are staged.
Of course, it's a simple matter to prove this- you can use an electric bike.
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it's the "pushing the air down" that actually keeps you up.
If you do the measurement in a wind tunnel you find that the pressure increase under a fairly simple aerofoil accounts for about 30% of the lift force at optimum AoA, and the pressure decrease over the upper surface, about 70%. That's why spoilers are fitted to the upper surface. A single-element aerofoil (Rogallo wing, sail) shows a smaller difference, and a flat surface will generate compression lift even if the upper surface is completely stalled.
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the people who build cycling robots are fraudsters
Not entirely, though they are certainly not contributing much to the sum of human happiness.
The stable capture range of negative feedback is fairly limited for a bike. Too much tube rake will make it difficult to turn and will absorb a lot of energy in the feedback mechanism, so gross movement of the rider is required to induce or oppose large tilt angles. https://www.bing.com/videos/search?q=motorbike+tube+angle&&view=detail&mid=3733E9AC47545AC580F83733E9AC47545AC580F8&&FORM=VDRVRV explains it very nicely.
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This video claims that we still don't know how bicycles work.
But somehow we can build self balancing bike.
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This video claims that we still don't know how bicycles work.
Interesting point. When a politician says "we" he means "you". When a journalist says "we" he means "I".
Images of penny-farthings and the like can be misleading because the front tube rake can be quite small - as little as 0.5 degree will confer some stability because the trail distance (from the front tube - ground intercept to the point of wheel contact) is large and, if the bike has solid tyres, fairly constant.
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explains it very nicely.
Wow!
It seems the terminology for rake has changed compared to the page I posted earlier.
https://www.cam.ac.uk/research/discussion/opinion-how-does-a-bike-stay-upright-surprisingly-its-all-in-the-mind
They now call it a "fork offset".
Are you labouring under the impression that the video actually explained why it was easy to fall off a Raleigh Chopper which has a small trail?
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It's a bit beside the point.
Q "What is the actual explanation of the gyroscopic effect?"
A "Actual physics."
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Offset is the distance the axle is ahead of the contact point. Reduced offset improves the response to intentional steering, increased trail improves stability.
Problem with small wheels is to get enough trail for hands-off stability without making the bike unsteerable.
Chopper instability probably involves seat tube angle and wheelbase too - there's far more information out there than I can be arsed to sum up!
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Which bit of
why
did you not understand?
When you answer, be sure to take account of the video hamdani yusuf posted which points out that you can even have a negative trail and still ride the bike.
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People have made bikes with contrarotating wheels to cancel that out, and they are still rideable.
People investigating bike stability have also made bikes with vertical forks (or even tilted-back forks) and they are still rideable - but it takes more practice, more effort and failures are more frequent.
I imagine that a bike with reversed steering (or wearing glasses that reversed left and right) would also be rideable - but you would have to unlearn a lot of childhood experiences before you could learn to ride it.
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People have made bikes with contrarotating wheels to cancel that out, and they are still rideable.
People investigating bike stability have also made bikes with vertical forks (or even tilted-back forks) and they are still rideable - but it takes more practice, more effort and failures are more frequent.
I imagine that a bike with reversed steering (or wearing glasses that reversed left and right) would also be rideable - but you would have to unlearn a lot of childhood experiences before you could learn to ride it.
Youtube also has videos about it.
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bike with reversed steering
The US Space Shuttle had a strange quirk that when gliding at hypersonic speeds, the effect of the left/right control surfaces was reversed, compared to the handling at lower speeds (and compared to all other aircraft).
- Because it was "fly by wire", they reversed the high-speed steering in software
- But I do wonder about the handling in the transition zone, where anything you did with the control surfaces would have no effect... :( Maybe it just flew like a paper dart...
Knowledge ≠ Understanding
I don't think riding a bike is a matter of knowledge or understanding - it is learned reflexes, at a subconscious level.
- Yes, you do engage knowledge and understanding when trying a new task
- But it eventually becomes learned at the subconscious level, and you can handle routine conditions without thinking about it (or while thinking about something entirely different)
- This is especially common with so-called "muscle memory", which is encoded in neurons well outside your frontal cortex (where our conscious thought resides)
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- But I do wonder about the handling in the transition zone, where anything you did with the control surfaces would have no effect... Maybe it just flew like a paper dart...
Perhaps they have secondary control option, like pressurized air throttle. They are more expensive, so they are only used for some specific cases where cheaper options fail.
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The US Space Shuttle had a strange quirk that when gliding at hypersonic speeds, the effect of the left/right control surfaces was reversed,
Was that rudder or aileron control? Or both?
Problem at hypersonic speed is that the compression front moves as you change attitude, so in addition to the low-speed lift and drag forces, you have something else shoving the aircraft around in a mode that you don't normally experience. Early "sound barrier" test pilots complained about locking control surfaces and also a supposed reversed control effect but that was all traceable to distortion of the aircraft.
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Yes, but I remember reading, until quite recently, that moving bicycles stay upright because of the gyroscopic effect created by the whirling wheels.
That was the orthodox theory. Now disproved, or so you claim.
It never appeared in any physics textbooks that I read. Bicycle wheels are designed to have the minimum moment of inertia consistent with their intended load and terrain. If you try to turn a heavy, spinning wheel, say to the left, it will try to flip you over to the right - not what we want on a bike!
Bicycle stability arises from the angle of the front tube. If you lean slightly to the left, the wheel turns to the left, so the bike starts to turn left and centrifugal force stops the bike from falling over. You can demonstrate this by making a bike with zero or negative tube angle, the latter being pretty impossible to ride.
Thanks Alan. That makes sense to me. The front end needs to be leading the direction of motion.
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Yes, but I remember reading, until quite recently, that moving bicycles stay upright because of the gyroscopic effect created by the whirling wheels.
That was the orthodox theory. Now disproved, or so you claim.
It never appeared in any physics textbooks that I read. Bicycle wheels are designed to have the minimum moment of inertia consistent with their intended load and terrain. If you try to turn a heavy, spinning wheel, say to the left, it will try to flip you over to the right - not what we want on a bike!
Bicycle stability arises from the angle of the front tube. If you lean slightly to the left, the wheel turns to the left, so the bike starts to turn left and centrifugal force stops the bike from falling over. You can demonstrate this by making a bike with zero or negative tube angle, the latter being pretty impossible to ride.
Thanks Alan. That makes sense to me. The front end needs to be leading the direction of motion.
Something that makes sense isn't always correct.
Which bit of
why
did you not understand?
When you answer, be sure to take account of the video hamdani yusuf posted which points out that you can even have a negative trail and still ride the bike.