A Brilliant IDEA

Discussion in 'Pseudoscience Archive' started by ABV, Jun 6, 2009.

  1. ABV Registered Senior Member

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    79
    The two words about IDEA.
    Let’s take a two rolling bodies on a track, a Thin Ring and a Solid Disk, with same mass and velocity.
    Are they have a difference? Yes. Kinetic Energy. On these conditions the Thin Ring has more kinetic energy than the Solid Disk has.
    Why? Because the rolling bodies full kinetic energy counts moment of inertia. Physics

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    Everybody knows.

    Let’s take a curve part of track. Would those rolling bodies gains different momentum to the track from centripetal force? NO. Because these rolling bodies have same mass and velocity.

    Let’s take a straight part of track. Inelastic rolling bodies are running without slippery.
    Would those rolling bodies gains different momentum to the track from Rolling Resistance?
    YES. Because these rolling bodies have a different moments of inertia.
    Why? Because, the Rolling Resistance is not a sliding friction. Under own weight the rolling bodies make a little cavity on the track and always hikes to this cavity edge. The rolling bodies are loosing a kinetic energy from that movement, but kinetic energy for the Thin Ring and Solid Disk with same conditions is different.

    Therefore, if construct an Isolated System with specific track, which has a curve and straight parts. The Isolated System will get a strange behavior.
    From one site, a law of momentums conservation must work.
    But from other site, a momentum from a Centripetal Force won’t compensate a momentum from a Rolling Resistance, on the Isolated System with Thin Ring.
    Paradox

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    Please take a look.
    hxxp://knol.google.com/k/alex-belov/paradox-of-classical-mechanics/1xmqm1l0s4ys/3#
     
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  3. CptBork Valued Senior Member

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    Momentum conservation doesn't apply to bodies under acceleration due to curved tracks and friction. You'd have to include the Earth in your calculations before you can invoke this.
     
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  5. ABV Registered Senior Member

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    79
    I agree with you. For real systems on Earth a calculations should include a gravity force.
    But this is a concept, which shows a paradox on classical mechanic world. The law of momentum conservation must work, but the rolling resistance with a thin ring on deceleration part gains a bigger momentum than centripetal force does.
     
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  7. AlphaNumeric Fully ionized Registered Senior Member

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    6,702
    No, it shows if you treat an open system (the rings exchange momentum with the Earth) as a closed system you get inconsistencies, which is true of any theory.

    WHEN YOU INCLUDE THE EARTH.

    You admit it's not including everything then proclaim it's inconsistent because you've assumed it has?! How stupid are you?
     
  8. ABV Registered Senior Member

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    79
    This is just a concept.
    I added a few more necessary forces into diagrams.
    Please take a look.
     
  9. AlphaNumeric Fully ionized Registered Senior Member

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    6,702
    But you're conceptually wrong. You view a non-closed system as closed and complain that it doesn't obey the properties of a closed system. The contradiction is with your understanding, not Newtonian mechanics.

    It's straight forward to show Newtonian mechanics is consistent with such things as energy and momentum conservation in your system, you just write down a Lagrangian it and see if it possesses any continuous symmetries. If it does then by Noether's theorem there's a conserved quantity for each symmetry. If not then it doesn't conserve that quantity. It's important to write down a Lagrangian for a closed system or else you will get incorrect results. In your case you have objects which interact with the Earth therefore you must include the Earth in your considerations of momentum, energy and angular momentum. If you don't then you could end up viewing the Earth's gravitational field as 'magic', it gives momentum to things without conserving momentum when infact it does, you just need to include the back reaction on the Earth.

    You're just wasting time with all your diagrams etc, you've failed to understand the theory and like all cranks you blame someone else.
     
  10. ABV Registered Senior Member

    Messages:
    79
    Thanks for good answer.
    I did not include gravity, because it may be any kind of force which helps to make a rolling resistance.
    Anyway. I am not try to crank a Newton laws. I just show a paradox for a thin rings inside a Isolated System. This is a concept and many people understand it.

    Thanks for you comments anyway.
     
  11. AlphaNumeric Fully ionized Registered Senior Member

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    6,702
    Except that it is not an isolated system. Gravity allows the rings and the Earth to interact, they are exchanging energy and momentum. So you have missed out part of the system.

    I know it's a concept, that doesn't mean you are magically right for ignoring part of the system. We don't have to go into details, we only need to deal with the broad concepts such as questions like "Are the rings an isolated system?". You say "Yes" but the answer is "No". Why? Because they are interacting with the Earth.

    Suppose you're modelling the motion of the Earth in the solar system. Do you consider the Earth a closed system or do you account for the fact the Sun exerts a force on it and it on the Sun? Of course you do otherwise it seems like the Earth is magically going in a circle.

    Even on concepts you are wrong. And yes, I do understand this, both conceptually and quantitatively. I have actually studied physics, unlike, I suspect, you.
     
  12. ABV Registered Senior Member

    Messages:
    79
    Let say, this system away from the Earth, somewhere in a deep space. lets exchange gravity force with electrostatic field.

    If you studied physics, you would easily understand a main idea of this concept and add all necessary conditions for Isolated System (if you need).
    I’m sorry if you don’t have "a free fly over a physics laws”. I could not help you.
     
  13. AlphaNumeric Fully ionized Registered Senior Member

    Messages:
    6,702
    And what's generating the electrostatic field? Whatever it is it will be exchanging momentum and energy with the disks.

    You seem to be missing the conceptual fundamentals here. Something pulls on the disks, be it the Earth gravitationally or some object electromagnetically. That 'something' is therefore part of the system and you must include it's energy and motion in your calculations. If you don't then you are not considering a closed system, you're considering part of a closed system and so you cannot and should not expect there to be energy and momentum conservation from the disks.

    Yeah, I understand it clearly a hell of a lot better than you. The disks are being acted upon by a force. What's causing the force? Some other object. By Newton's Third Law that object therefore experiences a back reaction and thus is part of the system. You cannot ignore it. If you do you don't have an isolated system.

    You are wrong.

    I suggest helping yourself first before trying to help anyone else. Well done on wasting considerable time on something a child can understand. Anyone who knows of Newton's Third Law should be able to spot your massive error.
     
  14. ABV Registered Senior Member

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    79
    On a straight track.
    The gravity force is perpendicular for rolling body movement. The gravity force do zero work for path without rolling resistance. And do work for path with rolling resistance. Or you forgot physics concept

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    ?
    But for simple model, just result rolling resistance force showed on diagram.


    A least it's not fear to tell it to unknown person for you.
    And based on your points, I may tell you just a pass physic course. Nut you don't know the physics as science.


    Please take a look on site. There is a lot of updates.
     
  15. AlphaNumeric Fully ionized Registered Senior Member

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    6,702
    If there's no rolling resistance then the disks never change their motion, they continue moving at their initial velocity and their angular momentum does not change. No problem. If there's rolling resistance then there must be a normal force between the disks and the surface, what makes that force? Electrostatic? Gravity? Back to the case I've already explained. Further more, if there's a normal force than there's a force exerted on the track and you must include its motion in your calculations, which is just a generalisation of including the ground when rolling the disks on Earth.

    No contradiction at all, other than in your understanding.

    I've a degree, masters and almost a PhD (a few months left) in applied mathematics and theoretical physics. Quite a bit more than what I imagine you have, a not too impressive pass at high school. Am I right?

    Update it all you want, doesn't make up for you ignoring parts of the system each and every time.
     
  16. ABV Registered Senior Member

    Messages:
    79
    Actually, did you read a doc or just look on first diagram?
    Please read first. You'll see there all explanations.

    At first, you are not correct.
    At second, if you have a physics degree, you may easily grab a main physics behavior from real process and construct deferential equation. Or simplify it to empirical formula for simple calculation. I hope it helps you to understand this concept.
    I impress, that some simple part start confuse you to understand the main idea of this concept.
    Or you didn’t read this doc? It may explain a lot

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  17. CptBork Valued Senior Member

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    Imagine you're standing on the Earth which is at rest in some reference frame, so neither you nor the Earth are moving in this frame. Then you decide to jump up. You have acquired momentum seemingly out of nowhere. But Newton's Third Law requires that an equal and opposite momentum be transferred to the Earth, even though this amount of momentum is far, far too small to make the Earth move by a noticeable amount. Thus by Newton's Third Law, the total momentum of the system consisting of you and the Earth remains at zero. Same thing goes for when you and the Earth come back together by equal and opposite gravitational tugs.

    So there's nothing strange, fishy, magical or contradictory going on here. Momentum conservation only works on closed systems in which all forces acting on the objects in this system originate from other objects in this same system. You can't take a donut or whatever, send it rolling, poke it with your finger and then claim momentum conservation is violated just because your finger deflected the donut.
     
  18. ABV Registered Senior Member

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    79
    Well, I thought about it.

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    And I am not a person, who wants a move without horsy

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    But the problem is rolling body with a big momentum of inertia though rolling resistance without slippery (no sliding friction) gains more momentum to a ground than rolling body with a big momentum of inertia. This makes sense for Isolated System. Once I started count difference for flywheel with low and high moment of inertia, I founded this miscalculation.
    So, idea is very simple. Centripetal forces momentums less than momentums from deceleration through rolling resistance for rolling bodies with high moment of inertia. This effect is not counted. Let’s do it now.

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  19. ABV Registered Senior Member

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    79
    Let’s do a simple part.
    Using differentiation equation, how would you describe movement for an inelastic rolling body with rolling resistance?
    I think this is very easy for you. Right?:shrug:
     
  20. AlphaNumeric Fully ionized Registered Senior Member

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    6,702
    It's NOT an isolated system, how can you not grasp that? Gravity has made them interact with the Earth!

    I dont need to do any calculus, I can (and have) immediately point out that you've ignored part of the system. Newton's Third Law says the change in momentum experienced by the disks will be cancelled by the change in momentum experienced by the Earth, since they have equal and opposite forces applied to them.

    Besides, you should have already done the equations, if you have put so much effort into this.
     
  21. ABV Registered Senior Member

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    79
    As I understand you can’t make a kinematical differential equation. Ok
    I have a question for you.
    What is different between sliding friction and rolling friction? Coefficient?
    But why each book says about cavity and rolling to the edge of cavity as a simple rolling resistance model?
    When you get a chance try to make a differential equation for this rolling resistance model. Do some theoretical practice. I hope it will very helpful for you

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  22. AlphaNumeric Fully ionized Registered Senior Member

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    You're jst trolling now and suspiciously like the usual idiot who tries to get me to respond, before he is promptly banned for the n'th time.

    If you knew any actual mechanics you'd know you don't write down a differential equation, you write down a Lagrangian, from which you can derive the equations of motion, which generally are differential equations, as well as being able to derive any conserved quantities.

    You have obviously never done that so it's a little silly you telling me to.

    The stuff I do day to day is much harder than what you're trying to prattle about.
     
  23. funkstar ratsknuf Valued Senior Member

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    1,390
    I have a Briliant IDEA too! The sun heats the earth, so when we consider the earth it's generating overunity energy! Lots of jiggawatts! PARADOX!

    /sarc
     

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