Offline edby

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Re: Increased gravity at the poles?
« Reply #60 on: November 13, 2018, 07:57:37 PM »
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
Both will have a platform to support the weighed object, and the platform will have a top and bottom. The upward force on the bottom equals downward force on top.

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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #61 on: November 13, 2018, 09:20:57 PM »
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
Both will have a platform to support the weighed object, and the platform will have a top and bottom. The upward force on the bottom equals downward force on top.

Do you see a box or container on these scales?




Offline edby

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Re: Increased gravity at the poles?
« Reply #62 on: November 13, 2018, 09:29:21 PM »
Do you see a box or container on these scales?
I used the term 'platform'.

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Offline markjo

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Re: Increased gravity at the poles?
« Reply #63 on: November 13, 2018, 09:30:28 PM »
Tom, the spring device will have a platform on which to place the object measured. The platform will have a top and a bottom surface. If the air flows freely, the force acting upwards on the bottom will be exactly equal to the force acting downwards at the top. Increase in atmospheric pressure will affect both equally, and will cancel out. If of course the air does not flow freely, and the pressure at the bottom is different from the top, this will affect the apparent weight. This will not normally happen.

Neither the spring scale experiment or the gnome experiment are described as using a box enclosure or a vacuum sealed enclosure.
High precision gravimeters are designed to be much more accurate than spring scales or the gnome experiment.  The spring scale and gnome experiments can act as poor man's gravimeters that can detect gravitational variations, just not as accurately as a dedicated gravimeter.  Gravitational variations are why scales must be calibrated locally using known reference masses. 

To borrow an argument from Thork, if air pressure was a factor in an object's weight, then you could get rich by buying precious metals on a cold stormy day when air pressure is low and selling on a bright sunny day when the air pressure is higher.
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Offline edby

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Re: Increased gravity at the poles?
« Reply #64 on: November 13, 2018, 09:48:20 PM »
This would make a good Flat Earth experiment. I have a barometer with me (currently reading 1036mb), and I can buy a digital weighing machine. Place 1 kg weight on the machine and plot the weight against different daily pressures. Any predictions on the result?

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #65 on: November 13, 2018, 10:23:02 PM »
Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
You can lead flat earthers to the curve but you can't make them think!

Offline edby

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Re: Increased gravity at the poles?
« Reply #66 on: November 13, 2018, 10:25:11 PM »
This is also a very strong test for the UA hypothesis. If the surface of the earth is a rigid plane and accelerating upwards at 9.8 m/s^2, it must be accelerating at the same rate at every point in the surface (otherwise it would deform). But this is inconsistent with the difference in weight that we seem to observe.

Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
I think the lead weight from the old clock will do just as well (unless you can lend me the gold).

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Offline Bobby Shafto

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Re: Increased gravity at the poles?
« Reply #67 on: November 13, 2018, 10:26:46 PM »
Yea, my predictions would be a variation in the micro-grams category, assuming you used a kg of gold as your weight.  Where did you say you lived?
My prediction would be any variation would not correlate with changes in air pressure.

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #68 on: November 13, 2018, 10:35:27 PM »
Maybe I can lend you some kryptonite.
The problems with a flat earth are even worse that that.  If you have UA, then you also have to find a way of accelerating the sun and moon as well.  They also need to be rotating which will require another energy source to keep everything moving in a circle (or maybe a pole with a cable).  That is, unless you want to forget Newton altogether.     
You can lead flat earthers to the curve but you can't make them think!

Offline edby

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Re: Increased gravity at the poles?
« Reply #69 on: November 14, 2018, 09:50:17 AM »
FYI this shows the pressure variation close to London. Currently around 1020. By contrast, the history of pressure at McMurdo shows a current range between 970 and 980, so pressure at the moment is much lower at high southerly latitudes.

Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight. However we do not observe this in the gnome experiment, where the variation is more like 0.5%, close to Clairaut’s prediction.

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #70 on: November 14, 2018, 03:28:13 PM »
I did some quick calculations.  I SWAGed it (Scientific Wild Ass Guess) and said that the volume of the Gnome was about 61.6 cm cubed.  I could have had Archeimedes give it a bath, but he isn't around anymore.  That means that the difference in weight due to the buoyancy of air at different densities due to change in atmospheric pressure would be about 4 millionths of a gram.  You wouldn't be able to see it on the Kern scale as good as it is.  Now the weight difference due to the measured difference in gravity at the poles and at the equator is a different story.  You can also apply the Somigliana equation to compensate for the effect of centrifugal force at different latitudes and you still come out with around a half percent difference in weight between the poles and the equator.  That's close to the measured difference in the weight observed in the traveling Gnome.  I suppose you could try to say that the flat earth is tumbling, but that doesn't even work.  As much as I hate to do it I'll give Tom a huge box of ammunition with the link: https://en.wikipedia.org/wiki/Spherical_cow.  I just thought that it applies to this situation.   
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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #71 on: November 14, 2018, 05:59:23 PM »
https://www.arlynscales.com/scale-knowledge/factors-can-affect-scales-accuracy/

Quote
Factors That Can Affect Your Scale’s Accuracy

...

Differences in air pressure – Scales can provide inaccurate measurements if the air pressure from the calibration environment is different than the operating environment.

Shocking. Both the spring scale experiment and the gnome experiment scales were calibrated for one environment and taken to another.

Offline edby

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Re: Increased gravity at the poles?
« Reply #72 on: November 14, 2018, 06:55:29 PM »
https://www.arlynscales.com/scale-knowledge/factors-can-affect-scales-accuracy/

Quote
Factors That Can Affect Your Scale’s Accuracy

...

Differences in air pressure – Scales can provide inaccurate measurements if the air pressure from the calibration environment is different than the operating environment.

Shocking. Both the spring scale experiment and the gnome experiment scales were calibrated for one environment and taken to another.
Causing an error of 4 micrograms, according to Ron above.

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #73 on: November 14, 2018, 07:01:15 PM »
The link you gave was for Arlyn Scales.  Of course, the Gnome was measured with a Kern scale.  The superior Kern scales can be compensated for your local conditions either at the factory before your item is shipped, or you can do it yourself.  All of that is irrelevant in this case anyway.  You are confusing the idea of mass and weight.  A mass standard is universal, at least on the planet earth, and is the resistance of that mass to being accelerated by a force.  There is an international standard for mass here on the earth.  Weight on the other hand is a measurement of the gravitational force on a given mass by the mass of the earth (usually).  The Kern scales can be compensated for your individual location before it’s shipped.  The whole idea of the Gnome exercise would be to explain that the earth’s gravitational force is different in different locations and is the reason that Kern should be paid extra to compensate your precision scale to your exact location.  Mass is much more difficult to measure than is weight.  If you have a compensated scale, then your weight and mass should be the same anywhere you measure it.  Shocking.
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Offline Tom Bishop

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Re: Increased gravity at the poles?
« Reply #74 on: November 14, 2018, 07:12:07 PM »
Causing an error of 4 micrograms, according to Ron above.

And according to you there can be a 6% difference:

Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.

Which expert opinion should we believe?

Offline edby

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Re: Increased gravity at the poles?
« Reply #75 on: November 14, 2018, 07:13:52 PM »
Causing an error of 4 micrograms, according to Ron above.

And according to you there can be a 6% difference:

Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.

Which expert opinion should we believe?

We should not believe experts. We should do the test ourselves. According to you, the 6% variation in pressure should lead to a 6% variation in weight. Is that your hypothesis? Yes or no?

(If you state the hypothesis clearly, I will buy some precision scales and calibrate them, then test against observed atmospheric pressure).

Offline edby

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Re: Increased gravity at the poles?
« Reply #76 on: November 14, 2018, 07:17:15 PM »
And according to you there can be a 6% difference:
Quote from: edby
Note also the range in London for the past two years is 980-1040, or about 6%. If Tom’s theory is correct, this should correspond to a 6% variation in weight.
Also, where did I say that there was a 6% difference in WEIGHT?? The '980-1040' range refers to atmospheric pressure, not the object weighed.

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #77 on: November 14, 2018, 07:21:00 PM »
There is some confusion here.  The 4 micrograms difference was just my estimation of the compensation needed due to the changes of atmospheric pressures.  The 6% variation in weights were due to the differences in the gravitational attraction of the standardized mass of the Gnome.  Probably 6% is a bit too high, it's probably closer to 5%, but it's still significant and still implies that the earth is not under a worldwide constant acceleration of 9.81 meters per second squared.  It also implies that the earth is not perfectly spherical and was the whole idea behind the experiment in the first place. 
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Offline edby

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Re: Increased gravity at the poles?
« Reply #78 on: November 14, 2018, 07:25:50 PM »
There is some confusion here.  The 4 micrograms difference was just my estimation of the compensation needed due to the changes of atmospheric pressures.  The 6% variation in weights were due to the differences in the gravitational attraction of the standardized mass of the Gnome.  Probably 6% is a bit too high, it's probably closer to 5%, but it's still significant and still implies that the earth is not under a worldwide constant acceleration of 9.81 meters per second squared.  It also implies that the earth is not perfectly spherical and was the whole idea behind the experiment in the first place.
Actually the 6% I was referring to was the 980-1040mb seasonal variation in pressure in London, which Tom confused with variation in weight, so there is a lot of confusion here, as usual.

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Offline RonJ

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Re: Increased gravity at the poles?
« Reply #79 on: November 14, 2018, 07:32:35 PM »
Besides that, if the earth were under a constant acceleration (UA) Kern wouldn't have to compensate their equipment for different locations.  I'm thinking that this isn't another government conspiracy.  I think the bigger worry would be that when I buy the next batch of unobtainium at the hardware store I'll have to watch that the salesman doesn't have his thumb on the scale.
You can lead flat earthers to the curve but you can't make them think!