Today is Earth's Rotation Day

Discussion in 'General Discussion' started by bernjb56, Jan 8, 2021.

  1. bernjb56

    bernjb56 Supporter

    In 1851, the French physicist Léon Foucault demonstrated how the earth rotates by suspending a lead-filled brass ball from the top of the Panthéon in Paris. This device, now known as the Foucault Pendulum, showed that the plane of the swing of the pendulum rotated relative to the Earth’s own rotation.

    Foucault Pendulums can now be found in science museums across the globe. Isaac Newton discovered gravity but he did not actually explain the cause behind it, merely that it exists as a force. The earth’s rotation is the cause for gravity and Foucault’s pendulums demonstrated this.

    It's going round and round :hattip:

    [​IMG]
     
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  2. So the French do have some uses?
     
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  3. I wish it was that simple. Gravity is affected by the spin of the Earth but it doesn’t cause it. I’ve yet to see a convincing explanation in layman’s terms of what does.

    Or as they used to say “the Earth sucks”.
     
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  4. Little Nellie

    Little Nellie Supporter

    My understanding is that Earth was formed from matter pulling together to form a planet. Gases, matter etc keeps swirling around and like a skaters arms when pulled towards his centre he spins faster. This would have been at big band time. You may have expected the rotation to slow down, but there are no forces in place to oppose it. Is why planets spin
     
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  5. Foucault's Pendulum is interesting - there is one in the London Science Museum which is set swinging every morning so that it makes a mark in a ridge of sand.
    However, Gravity has not yet been satisfactorily explained .
    Einstein reckoned that large masses such as planets etc. distort space so that a gravitational field is caused - but all masses cause this effect but are usually far too small to measure . The pendulum just shows that the Earth is moving and so displaces the pendulum slightly from its swing, with the help of gravity affecting the momentum - but does not explain what gravity is.
    Here endeth today's physics lesson.
     
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  6. We are slowing down. Days used to be nearer 25 hours, if not more.
     
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  7. Are you saying Glenn Miller is responsible? lovely thought.
     
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  8. Little Nellie

    Little Nellie Supporter

    Yep the universe was born to In the Mood, Brian Cox said so
     
  9. Poptop2

    Poptop2 Administrator

    Would you treat this grave subject with due gravitas and stop gravitating towards gratuitous humour please?
     
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  10. Down to earth me
     
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  11. Umm...gravity has nowt to do with the earth’s rotation. Nobody’s quite sure what it is. It’s the weakest (extremely weak) of known forces, although it may not seem like that if you jump off the roof of your house.

    Foucault’s Dangler demonstrates the inertia of a mass.
     
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  12. I thought at this moment in time, the Earth is spinning faster around its axis and the Moon is moving further away from Earth. I remember back in school days we used a simple pendulum to calculate g, the acceleration due to gravity. With a pendulum, g can be calculated fairly accurately. Give it a try.
     
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  13. bernjb56

    bernjb56 Supporter

    I’m just impressed that any of you have read my post :thumbsup:
     
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  14. Well remembered @mgbman - use T=2π√l/g. But when my students did it they were anything but accurate usually more than 10% out.
     
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  15. tbh
    its cold ,we're in lockdown ,its winter,
    we're stuck in with loved ones ...

    we'll read any old tosh ... :)
     
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  16. See me after class...
     
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  17. Little Nellie

    Little Nellie Supporter

    For two objects, Force due to gravity is proportional to the m1 x m2 over the distance separating the masses squared.

    So the bigger the two masses are and the shorter the distance that separates them, then the greater the force of gravity between them

    Still can’t tell my kids what gravity is though
     
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  18. Poptop2

    Poptop2 Administrator

    Are you an electrician?
     
  19. Soggz

    Soggz An inquisitive supporter



    Someone had to do it...
     
  20. Ah - gravitas

    A suitably grand term for the branch of science that studies the consistency and flow characteristics of....................gravy.
     
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