# Thread: PHYSICS: Foucalt's Pendulum and The Unflat Earth

1. ## PHYSICS: Foucalt's Pendulum and The Unflat Earth

LINKY

I was watching this pendulum at the University of Osnabrück, and thinking "okay, this proves that Earth rotates".

Now, I'm not really good at all where physics is concerned, but if Earth was a disc, wouldn't there be some sideways slew on a pendulum, the closer one got to the perimeter?

My mind is hurting, and an explainer who's good at talking to the simple would be welcome.

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## Re: PHYSICS: Foucalt's Pendulum and The Unflat Earth

The Irreverent Mr Black said
LINKY

I was watching this pendulum at the University of Osnabrück, and thinking "okay, this proves that Earth rotates".

Now, I'm not really good at all where physics is concerned, but if Earth was a disc, wouldn't there be some sideways slew on a pendulum, the closer one got to the perimeter?

My mind is hurting, and an explainer who's good at talking to the simple would be welcome.

No because it's the coriolis effect that causes the pendulum to change direction, and on a flat body there's no coriolis effect. The pendulum on a flat body wouldn't swing straight but it would swing in a fixed manner not a constantly moving manner. No matter which direction you started it swinging it would always end up swinging on a line between the rim and centre of the flat rotating earth due to the centripetal force.

I think that covers it!

3. ## Re: PHYSICS: Foucalt's Pendulum and The Unflat Earth

LINKY tells me you can calculate latitude with a pendulum. I think that's what you were explaining.

The Flurfers have had a go here: https://www.theflatearthsociety.org/...?topic=70278.0

and here: https://www.theflatearthsociety.org/...?topic=61282.0

Looks like the pendulum proves rotation, but has nothing definitive to say on planar/spherical Earth.

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## Re: PHYSICS: Foucalt's Pendulum and The Unflat Earth

The Irreverent Mr Black said
LINKY tells me you can calculate latitude with a pendulum. I think that's what you were explaining.

The Flurfers have had a go here: https://www.theflatearthsociety.org/...?topic=70278.0

and here: https://www.theflatearthsociety.org/...?topic=61282.0

Looks like the pendulum proves rotation, but has nothing definitive to say on planar/spherical Earth.
Ah but the thing is the pendulum changes with laititude due to differing strength of the coriolis effect, at the equator it shouldn't move at all, north of the equator it will go one direction, south of the equator it will turn the opposite way, this can only happen with a spherical rotating earth, not a flat rotating earth.

5. ## Re: PHYSICS: Foucalt's Pendulum and The Unflat Earth

@SteveB: Gotcha! Thanks.

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