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  • measuring earth's rotation via Focault

    From Retrograde@fungus@amongus.com.invalid to sci.misc on Tue May 26 22:10:46 2026
    From Newsgroup: sci.misc

    From the -2burn it to turn it-+ department:
    Feed: Hackaday
    Title: Measure the EarthrCOs Rotation Victorian Style
    Author: Al Williams
    Date: Wed, 13 May 2026 14:00:33 +0000
    Link: https://hackaday.com/2026/05/13/measure-the-earths-rotation-victorian-style/
    Podcast Download URL: https://hackaday.com/wp-content/uploads/2026/05/pend.png

    [image 1 (link #1)]

    YourCOve probably seen a Foucault pendulum in a museum. This Victorian-era science demonstration is named after physicist L|-on Foucault and shows
    how the Earth rotates compared to a pendulum moving in a fixed plane. [RyanCreates] shows you how you can make your own[2], and it is
    surprisingly simple.

    All you need is a heavy weight like a small mushroom anchor, fishing
    line, and a swivel rCo all things you can pick up at any sporting goods
    store. YourCOll need a way to suspend it all, such as an eye hook in the ceiling.

    In addition to the mechanical parts, the build calls for a camera to
    record the results and a lighter or other source of flame. The reason?
    To release the pendulum, you burn a thread that prevents it from
    swinging. This allows for a clean release with no sideways force.

    The amount of your rotation depends on your latitude. At 33 degrees
    north, for example, you can expect 360*sin(33)/24 or 8.17 degrees per
    hour of rotation. [Ryan] measured a somewhat larger number, which was
    probably due to an error source, especially since he is measuring the
    angle using captured camera frames in Photoshop. That has to introduce
    some error, and small pendulums like this are incredibly sensitive to
    errors.

    If you try it and find the source of the error, werCOre sure [Ryan] would
    love to hear from you. Museum pieces[3] are typically much larger, have ultra-low-friction pivots, and use electromagnets to keep the pendulum
    moving since, after all, even a Foucault pendulum canrCOt run forever.

    Links:
    [1]: https://hackaday.com/wp-content/uploads/2026/05/pend.png?w=742 (image) [2]: https://www.instructables.com/Proving-Earths-Rotation-With-a-DIY-Foucault-Pendul (link)
    [3]: https://hackaday.com/2025/12/27/what-to-do-when-your-foucault-pendulum-stops-swinging/ (link)

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  • From Mikko@mikko.levanto@iki.fi to sci.misc on Wed May 27 10:43:44 2026
    From Newsgroup: sci.misc

    On 27/05/2026 01:10, Retrograde wrote:
    From the -2burn it to turn it-+ department:
    Feed: Hackaday
    Title: Measure the EarthrCOs Rotation Victorian Style
    Author: Al Williams
    Date: Wed, 13 May 2026 14:00:33 +0000
    Link: https://hackaday.com/2026/05/13/measure-the-earths-rotation-victorian-style/
    Podcast Download URL: https://hackaday.com/wp-content/uploads/2026/05/pend.png

    [image 1 (link #1)]

    YourCOve probably seen a Foucault pendulum in a museum. This Victorian-era science demonstration is named after physicist L|-on Foucault and shows
    how the Earth rotates compared to a pendulum moving in a fixed plane. [RyanCreates] shows you how you can make your own[2], and it is
    surprisingly simple.

    All you need is a heavy weight like a small mushroom anchor, fishing
    line, and a swivel rCo all things you can pick up at any sporting goods store. YourCOll need a way to suspend it all, such as an eye hook in the ceiling.

    In addition to the mechanical parts, the build calls for a camera to
    record the results and a lighter or other source of flame. The reason?
    To release the pendulum, you burn a thread that prevents it from
    swinging. This allows for a clean release with no sideways force.

    The amount of your rotation depends on your latitude. At 33 degrees
    north, for example, you can expect 360*sin(33)/24 or 8.17 degrees per
    hour of rotation. [Ryan] measured a somewhat larger number, which was probably due to an error source, especially since he is measuring the
    angle using captured camera frames in Photoshop. That has to introduce
    some error, and small pendulums like this are incredibly sensitive to
    errors.

    If you try it and find the source of the error, werCOre sure [Ryan] would love to hear from you. Museum pieces[3] are typically much larger, have ultra-low-friction pivots, and use electromagnets to keep the pendulum
    moving since, after all, even a Foucault pendulum canrCOt run forever.

    Because of that error Earth's rotation cannot be measured with a
    pendulum unless the latitude is known. But Foucault invented another
    device that doesn't have that defect: gyroscope.
    --
    Mikko
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