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Thread: magnet setting going wrong somehow

  1. #1 magnet setting going wrong somehow 
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    Hello all,

    I fell on this science website where I thought I might find some help.

    I am looking at an answer. I explain.

    I have some 25 X 10 X 3 (all mm) magnets.

    Apparently the poles are on the length (on the longest faces) of them.

    I wanted to reproduce what I had done at my step dad in France so I set up a “wheel”. it is ashame I can not input a drawing here because I have one.



    Basically the magnets are standing up right separated by a piece of plastic following a perimeter. The flattest and largest face of them facing toward the center of the circle. There is 1 magnet upright, then 2 together upright next to the first one, then 3 together next to the previous group of 2 magnets together, then 4 together etc.... up to 8 magnets packed together. Between all rows of magnets (the plastic pieces are not shown on my drawing) on a perimeter.


    In the middle stands a metal needle on a small shaft (mounted on the shaft of a roller skate bearing).

    What I had done at my step dad was about the same but in a glass and the needle went straight from magnet 1 to 8.

    When I did this on my new “wheel”, it amazingly become weird!!! The needle gets stucked on the first one… it can go and get stuck up to the fourth… I do not understand.

    I have measured than 2 magnets attract more than one, than 3 attract more than 2 etc. So I was thinking that it will go straight from 1 to 8 but NO.

    I am frustrated especially because I do not understand why and I can not reproduce what I have done at my step dad?




    CAN YOU EXPLAIN THIS? Where is my mistake?

    If you want a picture I can send it to you, my email is tradurol@fsmail.net


    PS; thanks for the website



    Roland Bouchat, Peel, Isle of Man
    :-D :-D :-D


    Roland

    "Politicians, they would eat wax to shine"
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  3. #2  
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    I have a bit of experience with magnets. Can you post a picture, or link to some online picture-storing site? It's hard to visualise just from the text.


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  4. #3 a video on youtube 
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    Yes, sure thing. I made a small video about it, it is there:

    http://www.youtube.com/watch?v=4tjoIjWVzac


    Roland
    Roland

    "Politicians, they would eat wax to shine"
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  5. #4  
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    Sorry about the very late reaction. I only now found the time to watch you video. I think I see what you are trying to do. The problem seems to be that there are energy pits for the rotating magnets to get stuck in. But even if you would eliminate the energy pits (or get the energy "mountains" small enough to be overcome by accumulated kinetic energy, something that might be done by making the magnets on the rotor wider; you can also use a piece of iron instead of a magnet on the rotor), you would never go more than a quarter turn if you have a rotor with four magnets. A magnet going from the largest to the smallest magnet would need to climb a very steep energy mountain, which is at least as large as the total kinetic energy you could possibly have accumulated, but necessarily smaller, since you lost energy to friction.

    If you where trying to make a perpetuum mobile: a device that keeps moving without adding energy, or even creates energy, you could only fail, since that is, of course, impossible.
    The thing is that if you don't add energy in any way, you can't increase the kinetic energy.

    I hope this helps.
    cheers,
    Bender
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