Offline edby

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Increased gravity at the poles?
« on: November 11, 2018, 11:45:23 AM »
From the Wikipedia article on Clairaut's theorem:
Quote
https://en.wikipedia.org/wiki/Clairaut%27s_theorem Although it had been known since antiquity that the Earth was spherical, by the 17th century evidence was accumulating that it was not a perfect sphere. In 1672 Jean Richer found the first evidence that gravity was not constant over the Earth (as it would be if the Earth were a sphere); he took a pendulum clock to Cayenne, French Guiana and found that it lost 2 ½ minutes per day compared to its rate at Paris. This indicated the acceleration of gravity was less at Cayenne than at Paris. Pendulum gravimeters began to be taken on voyages to remote parts of the world, and it was slowly discovered that gravity increases smoothly with increasing latitude, gravitational acceleration being about 0.5% greater at the poles than at the equator.
How would FE theory explain this result? As usual there are two questions (i) whether the observation is correct and (ii) if correct, how would FE theory explain the difference in gravity?

This is different from the height effect, whereby gravity decreases with height. This is explained by Celestial Gravitation. The Clairaut phenomenon, by contrast, is a surface effect, dependent only on latitude.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #1 on: November 11, 2018, 09:38:39 PM »
Firstly, in specific to your quote about the pendulum clock, it seems difficult to trust that a pendulum clock would maintain its constant rate when being moved and jostled over such a great distance.

Secondly, to address your point, the reason advanced by the wider Flat Earth movement for why there is more weight at the poles is due to two factors:

1. The atmosphere has weight, and atmospheric pressure "pushes down" on us.

See the following illustration:



2. The barometric pressure is higher at the poles

See  https://en.wikipedia.org/wiki/Polar_High

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Polar High

The polar highs are areas of high atmospheric pressure around the north and south poles; the north polar high being the stronger one because land gains and loses heat more effectively than sea. The cold temperatures in the polar regions cause air to descend to create the high pressure (a process called subsidence), just as the warm temperatures around the equator cause air to rise to create the low pressure intertropical convergence zone.

Ergo, if there is more pushing pressure, due to the Polar Highs, we will weigh more at the poles.
« Last Edit: November 12, 2018, 06:40:55 PM by Tom Bishop »

Offline edby

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Re: Increased gravity at the poles?
« Reply #2 on: November 12, 2018, 09:21:38 AM »
1. The atmosphere has weight, and atmospheric pressure "pushes down" on us.
2. The barometric pressure is higher at the poles

See  https://en.wikipedia.org/wiki/Polar_High
[…]
Ergo, if there is more pushing pressure, due to the Polar Highs, we will weigh more at the poles.
Interesting. This could easily be measured and tested. If my weight goes up and down with atmospheric pressure, we could draw up a scatter chart showing the correlation.

Doesn't this conflict with the standard 'scientific' view that weight goes down with pressure? This is why humans float in water, for instance.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #3 on: November 12, 2018, 03:59:16 PM »
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?

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Offline Boots

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Re: Increased gravity at the poles?
« Reply #4 on: November 12, 2018, 04:03:56 PM »
A rock underwater will weigh 2/3 of what a rock on the beach weighs.
Where the senses fail us, reason must step in. - Galileo Galilei

Offline edby

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Re: Increased gravity at the poles?
« Reply #5 on: November 12, 2018, 05:02:03 PM »
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?

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https://www.soest.hawaii.edu/GG/ASK/weight.html
Would a person weigh more in a denser atmosphere than in a less dense atmosphere? Does the pressure exerted by a column of air cause changes in a person's weight?
 
Actually, a person would weigh less in a denser atmosphere. "Weight" is how much you push down on a scale - which is different from "mass" which is how much matter you contain (which wouldn't change). The formula is: weight= mass*(gravitational acceleration). The pressure exerted by a column of air is the same in all directions, so a heavy atmosphere does not have weight since it pushes just as much up as it does down. What makes your weight be less in a heavy atmosphere is the buoyancy effect - your volume is taking up space that would normally be taken by the heavy air, and the mass of the displaced air is subtracted from your mass when calculating weight: your weight=(your mass-displaced air mass)*(acceleration of gravity). Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float.

Dr. Fred Duennebier, Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu

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Offline Bobby Shafto

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Re: Increased gravity at the poles?
« Reply #6 on: November 12, 2018, 05:38:04 PM »
I don't see why weight would go down with pressure.

I think the confusion stems from the erroneous belief that air pressure has a vector: i.e. "pushing down."

Air pressure is not measured like weight. It's not additive to weight as your proposed FET solution to the OP question presumes.

If the earth's atmosphere suddenly disappeared, you'd weigh the same. (Or, if have the ability to measure very precisely, you'd find your weight increased ever so slightly due to the loss of buoyancy.)

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #7 on: November 12, 2018, 06:04:37 PM »
It is not an "FE belief":

http://www.weatherquestions.com/How_much_does_air_weigh.htm

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How much does air weigh?

It might not seem like it, but air has weight. Anything with mass has weight, and we know air has mass because (for example) we can feel it when the wind blows. The total weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch at sea level.
« Last Edit: November 12, 2018, 06:07:58 PM by Tom Bishop »

Offline edby

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Re: Increased gravity at the poles?
« Reply #8 on: November 12, 2018, 06:13:27 PM »
http://www.weatherquestions.com/How_much_does_air_weigh.htm
The total weight of the atmosphere exerts a pressure of about 14.7 pounds per square inch at sea level.

Correct, and so it exerts that pressure on the bathroom scales even when no one is standing on them. When I now stand on them, the result is my additional weight, i.e. my weight in a vacuum.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #9 on: November 12, 2018, 06:58:54 PM »
I don't see why weight would go down with pressure. You are talking about buyancy and density of objects, which is a different subject.

Will a boulder feel more weight on the beach or on the bottom of the ocean?

Quote
https://www.soest.hawaii.edu/GG/ASK/weight.html
Would a person weigh more in a denser atmosphere than in a less dense atmosphere? Does the pressure exerted by a column of air cause changes in a person's weight?
 
Actually, a person would weigh less in a denser atmosphere. "Weight" is how much you push down on a scale - which is different from "mass" which is how much matter you contain (which wouldn't change). The formula is: weight= mass*(gravitational acceleration). The pressure exerted by a column of air is the same in all directions, so a heavy atmosphere does not have weight since it pushes just as much up as it does down. What makes your weight be less in a heavy atmosphere is the buoyancy effect - your volume is taking up space that would normally be taken by the heavy air, and the mass of the displaced air is subtracted from your mass when calculating weight: your weight=(your mass-displaced air mass)*(acceleration of gravity). Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float.

Dr. Fred Duennebier, Professor
Department of Geology and Geophysics
University of Hawaii, Honolulu

As it says in that quote: it does not equal out to be zero.

"Actually, a person would weigh less in a denser atmosphere."

Also:

"Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float."

And it follows form that if the mass weighs more than the displaced air the mass will sink and be 'heavier'.

When he says that humans would weigh less in a high pressure environment he is talking about human density specifically, which is not the densest material, exemplified by the fact that human bodies easily float in water.

If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.

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Offline stack

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Re: Increased gravity at the poles?
« Reply #10 on: November 12, 2018, 07:00:07 PM »
If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.

Is it fundamentally different or just that the two have different densities?
Not much is known about the celestial bodies and their distances.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #11 on: November 12, 2018, 07:01:10 PM »
If we consider a lead weight on a scale at the bottom of a swimming pool it is a fundamentally different scenario when compared with a human on a scale at the bottom of a swimming pool.

Is it fundamentally different or just that the two have different densities?

Being pushed up is fundamentally different than being pushed down, yes.

Offline edby

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Re: Increased gravity at the poles?
« Reply #12 on: November 12, 2018, 07:06:50 PM »
Once again. Suppose there is a 1 kg weight on the bathroom scales. I remove the weight, and while still carrying it, I now stand on the scales. By how much will the weighed amount increase?

So it is with the air. There is a big column of air on the bathroom scales. As soon as I step on the scales, I remove the direct effect of the air, but it remains because it is sitting on my head, as it were.

Buoyancy, as Tom rightly says, is something else. However, buoyancy would cause my weight on average to decrease at the poles, not increase, as Tom claims. I say 'on average' because the daily change in atmospheric pressure in London is far greater than the average difference between London and the poles.

My questions remain. (1) Do things weigh more at the poles and if so (2) why is that? 

Offline edby

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Re: Increased gravity at the poles?
« Reply #13 on: November 12, 2018, 07:21:05 PM »
As it happens, the pressure in London is greater than at the South Pole, at least today.

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Offline Bobby Shafto

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Re: Increased gravity at the poles?
« Reply #14 on: November 12, 2018, 07:23:22 PM »
It is not an "FE belief"
If you are saying (incorrectly) that barometric pressure is the "weight of air" to make a flat earth argument that greater air pressure increases weight, then that's a flat earth belief.

You are conflating earth-shape agnostic truths to arrive at an erroneous conclusion.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #15 on: November 12, 2018, 07:24:59 PM »
My questions remain. (1) Do things weigh more at the poles and if so (2) why is that?

I believe that your source answered it. If the mass of the object is equal to the air it displaced it is neither pushed upwards or downwards, if the mass of the object is less than the air it displaces, it is pushed upwards/lighter and if the mass of the object is more than the air it displaces it is pushed downwards/heavier.

Since the poles are generally of higher pressure, those effects will manifest greater there.
« Last Edit: November 12, 2018, 07:27:17 PM by Tom Bishop »

Offline edby

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Re: Increased gravity at the poles?
« Reply #16 on: November 12, 2018, 07:37:18 PM »
My questions remain. (1) Do things weigh more at the poles and if so (2) why is that?

I believe that your source answered it. If the mass of the object is equal to the air it displaced it is neither pushed upwards or downwards, if the mass of the object is less than the air it displaces, it is pushed upwards/lighter and if the mass of the object is more than the air it displaces it is pushed downwards/heavier.

Since the poles are generally of higher pressure, those effects will manifest greater there.
So things will be (slightly) lighter at the poles, if it were only down to atmospheric pressure. But they are heavier. Why?

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #17 on: November 12, 2018, 07:50:56 PM »
Quote
So things will be (slightly) lighter at the poles, if it were only down to atmospheric pressure. But they are heavier. Why?

It's only lighter at the poles if it's an object that is of low density, and lighter than the air it displaces. If the object is of high density, heavier than the air it displaces, the opposite effect will occur. If the object is at equal density to the air it displaces it will be neigher lighter or heavier.

From what I looked at the from the experiments, they are measuring metallic weights on scales.
« Last Edit: November 12, 2018, 08:01:12 PM by Tom Bishop »

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Offline markjo

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Re: Increased gravity at the poles?
« Reply #18 on: November 12, 2018, 07:51:58 PM »
"Note that if the mass of displaced air is equal to your mass, you will weigh nothing (neutral buoyancy), and if you weigh less than the displaced air (as you do in water) you will float."

And it follows form that if the mass weighs more than the displaced air the mass will sink and be 'heavier'.
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

This link provides a pretty good explanation of buoyancy and points out a few things that may be confusing:
Surprisingly the buoyant force doesn't depend on the overall depth of the object submerged. In other words, as long as the can of beans is fully submerged, bringing it to a deeper and deeper depth will not change the buoyant force. This might seem strange since the pressure gets larger as you descend to deeper depths. But the key idea is that the pressures at the top and bottom of the can will both increase by the same amount and therefore cancel, leaving the total buoyant force the same.
Abandon hope all ye who press enter here.

Science is what happens when preconception meets verification.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #19 on: November 12, 2018, 07:57:56 PM »
Tom, in a nutshell, Archimedes Principle says:  "Every object is buoyed upwards by a force equal to the weight of the fluid the object displaces."  This means that dense objects will always become lighter as the density of the fluid displaced increases.

That is not what that quote means. It means that if the weight of the object is equal to the fluid it displaces it will pulled neither lower or higher.

But if the object is lighter than the fluid it displaces it will be pulled higher. Just the same, if the object is heavier than the fluid it displaces it will be pushed lower.
« Last Edit: November 12, 2018, 07:59:43 PM by Tom Bishop »