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OT?...How does gravity vary?

Pendulum clocks - the usual electronic movement type (battery feedback pulses solenoid when magnet on pendulum passes by).

My experience with these movements is that they are somewhat delicate: you have to carefully adjust the clock movement vertically and horizontally until the pendulum swings reliably.

However after running for several hours, sometimes the pendulum stops. I think that I've ruled out the battery as the guilty party. That set me to wondering: does gravity vary? If so, what are its characteristics? Could gravity changes account for the pendulum stopping?

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Roy
[Surrey, England]
Reply to
Roy Hammond
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Try a horizontal pendulum. It would be independent of gravity.

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Reply to
Don Lancaster

Yes. Sometimes the heavy gravity sits as a layer on top of the light gravity and holds it down causing a gravity inversion layer.

Reply to
Homer J Simpson

Gravity varies a little bit due to the effects of the sun and moon (which is why we have tides) but I doubt that this is the reason for your clock stopping.

Gravity also decreases with increased altitude, and is slightly different at different places on the Earth's surface due to different local geology.

A gravitational force of attraction exists between any objects with mass, so in theory moving any object would cause a change in the total gravitational force seen by the pendulum. However, the Earth is very large and close, so most other things will not cause any detectable change.

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Reply to
Gareth

I don't think variations in gravity are stopping your clock. I have one that has been running on one AA battery for about 2 years.

The pendulum needs to be aligned not only in the lateral plane (side to side so that it swings equally to either side of the solenoid mechanism), it needs to be aligned fore and aft so that the pendulum's bearing (usually some sort of blade or wedge shape) makes contact with its rest with minimal friction.

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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Reply to
Paul Hovnanian P.E.

And when teenage boys watch p*rn the reverse seems to happen in their pants!

Reply to
Homer J Simpson

Nope! No observable reason for it to stop other than dirt accumulated in the bearings due to (too much) oil. The force of gravity changes with locale; known to be stronger near large deposits of iron. Extremely doubtful of local "modulations", and the variations mentioned above are very small.

Reply to
Robert Baer

As the hippy would say, "Heavy, man!".

Reply to
Robert Baer

Hmm. I thought that was due to the gravitational attraction to satellites passing overhead.

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Paul Hovnanian     mailto:Paul@Hovnanian.com
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Reply to
Paul Hovnanian P.E.

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