How much you weigh, depends upon where you are on the Earth - because it's a rotating sphere

Dear Readers,

Here is a simply inexpensive experiment that you can do, to prove that the Earth is a curved globe. You don't need to be a rocket scientist or proficient in physics. You just need common sense.

The following table lists how much a 500-gram object would weigh at different (north - south) points on the Earth.

This table lists Earth latitude verses 500 grams of weight...

Latitude	How much does 500 grams weigh
90°	500.0000
80°	499.6986
70°	499.4064
60°	499.1326
50°	498.8855
40°	498.6726
30°	498.5002
20°	498.3733
10°	498.2957
0°	498.2696

So then basically, the same object that weighs of 500 grams at the North Pole, will weigh 498.2696 grams at the Earth's equator.

So what does this prove, if anything?

It proves that the Earth is a rotating ball, since those are weight measurement changes simply due to spin (once per day)

First off, the Earth spins like a top. It rotates once around every day (23-hours, 56-minutes and 4-seconds). As you can see from the picture below, since the Earth is round the center (equator) spins at a faster rate than any location farther north or south.

As an example,

in Salt Lake City USA, where the latitude is 40.76° north, it spins at 786 mph.

in Atlanta Georgia USA, where the latitude is 33.75° north, it spins at 863 mph

in Miami Fla USA, where the latitude is 25.76° north, it spins at 934 mph

and at Macapa Brazil, where the latitude is 0.04° north, it spins at 1037 mph

The faster you spin, the greater the force is that wants to throw you off, called the apparent centrifugal force. That force is opposite to the direction of gravity, so all objects weigh slightly less because of it.

Earth rotational speed by latitude.png

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Centripetal verses centrifugal forces of circular motion...

When you twirl a ball on a rope like the man in the diagram below, you can feel the tug of the ball, as it wants to fly off away from you. That tug is apparent centrifugal force.

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Remember going to the amusement park and riding the Rotor?

And then once you start to spin fast enough, the floor drops away...

And the reason you don't fall down is because you are plastered to the wall by apparent centrifugal force.

Same as the apparent centrifugal force (0.0339 meters/sec/sec acceleration) acting on your body in Macapa Brazil, trying to throw you off the Earth.

Now find out for yourself:

So calibrate your weigh scale to read 500 grams at home.

Then take a road trip either north or south of where you live. When you come to a stop (preferable several hundred miles away) measure the weight again. Record your measurements in a log book. Then head further down the road and measure again. The more stops and measurements you take the better your data will be.

When you’re done with the trip:

Now take out your log book and measure the differences in weight between your different stops. A difference indicates that the Earth is round and spinning.

But to more precise, note the latitude of the locations where you made the measurements. Then refer to the table above and compare those weight differences to what you found.

Say your log book looks like this:



Location	Latitude of location	weight of the 500 gram sample

home is Atlanta GA USA	33.7490° N	500.00

Knoxville TN USA	35.9606° N	500.45

Columbus OH USA	39.9612° N	500.90

Detroit MI USA	42.3314° N	501.35

The difference in your measured weight between your different locations (about 0.45 grams each) is what should be expected based on the round spinning Earth calculations shown in the tables at the bottom of this post.

Conclusion? You're done and you proved that the Earth is a spinning globe! CONGRATULATIONS!

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Before you start your trip you need to also understand how a city's elevation above sea level can influence your measurements, and contribute to a possible error of about 5%. We want to minimize this.

The general rule is that due to the force of gravity, the lower the elevation, the less an object will weigh. That is because, as an example, there is less Earth material below your feet at sea level than on a high mountain. Less mass under your feet means less gravitational pull.

So for example, the 500-gram standard at Atlanta, Georgia, will weigh 0.05 grams more than at sea level, just because of the city's altitude (1,050 above sea level).

Here is the mathematical gravitational physics formula for calculating the effect of altitude on weight...

So again for Atlanta, (elev. 1050 feet / radius of the Earth) = (20904570 feet / 20903520 feet) = a value for g = 9.799016 for Atlanta, as opposed to 9.8 at elevation = 0 = sea level. That equates to a weight change of 0.05 grams.

Although that influence on your trip measurements is minimal, we would still like to eliminate it.

Therefore, we recommend that on your trip, your starting and ending city be at about the same altitude above sea level.

For example,
from Atlanta Georgia (1,086 feet) to Cleveland Ohio (1,050 feet)
from Charlotte North Carolina (784 feet) to Milwaukee Wisconsin (799 feet)
etc.

So come on. There are many many North or South trips that you can take, where the FROM and TO cities are about at the same elevation.

So hit the road and enjoy the scenery, and learn about the true shape of our beautiful magnificent globe Earth.

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Reference 1 - here is a video by Wolf6020, which is THE START of his road trip documentary checking a 500 gram weight from several different locations on the Earth. Wolf6020 says he will over the next year post other videos showing his weight measurements from other Earth locations.

Flat Earth vs Globe - Does weight change with Latitude? Is this evidence the Earth is spinning?
https://www.youtube.com/watch?v=CkhxPm15PFo

The weight scale he used - https://www.amazon.com/Smart-Weigh-Back-Lit-Features-Included/dp/B00ME8VI34

His 500 gram weight - https://www.amazon.com/American-Weigh-Scales-500WGT-Calibration/dp/B00SSK3YNO

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Reference 2 - here is a video by Wolf6020, that shows weight stays the same while traveling west to east; as should be expected from the centrifugal force explanation given above.

Flat Earth vs Globe; Real evidence that aircraft follow the Earth's curvature
https://www.youtube.com/watch?v=zX3upPW7uw4&t=514s

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Why doesn’t Earth’s rotation fling us off in to space?

Gravity attracts all objects toward the Earth’s center. The acceleration due to gravity at Earth’s surface is 9.8 meters per second, per second.

Centripetal force on Earth is the force of gravity acting on objects (us) orbiting Earth – we happen to orbit the Earth on its surface, at its exact speed of rotation, because gravity “glues” us to the surface as the Earth spins on its rotational axis.

Centrifugal force is the unbalanced reaction of inertia to centripetal force.

So centripetal force constantly “pulls” us toward the Earth as we orbit, while “centrifugal” force is the inertial tendency of mass (our bodies) to continue moving in a straight line (e.g. flung in to space).

The pound (lbs), in normal reference, is a unit of weight (force). The kilogram is a unit of mass.

Force = Mass * Acceleration (F=ma)

Now some calculations:

Earth’s circumference at the equator is about (40,075 km / 24901 miles). At the equator, Earth’s surface moves at about v=465 m/s (1,040 mph).

The Earth’s rate of rotation (w) is about 15 degrees per hour (.0042 deg/s), which of course equals one full rotation per day.

The Earth’s average radius (r=center to surface) is about 6,370 km.

Centripetal acceleration at the equator, a = v^2/r, is about .034 m/s/s.

Since this minuscule force of .034 m/s/s - is only 0.34% of the force of gravity, it is nowhere strong enough to throw anyone off the Earth.

That being the case, we can also solve for how fast would the Earth need to spin in order for someone on the surface at the equator - to become weightless. That answer is one earth rotation (1 day & 1 night) every 84-minutes.

So if the Earth were to rotate faster than once every 84-minutes (not once every 24-hours as it does now) you would be flung off into the atmosphere.

The latitude, measured in degrees, of a given location starts at 0 at the equator, and ends at 90 degrees at the north or south pole. Drawing a line from the center of the Earth, this would be the angle at which the line is deflected from its nearest point on the equator.

In the United States, the mean latitude is about 39 degrees, ranging from about 29.76 degrees in Houston, TX to about 48.23 degrees in Minot, ND.

As you move north, the distance of the surface from its axis of rotation decreases. At the mean US latitude, the radius from the surface to the axis of rotation is only about 4,951 km.

At 39 degrees north latitude, the Earth’s linear velocity (at the surface) is about 360 m/s (811 mph).

The resulting centripetal acceleration (a=v^2/r) is .026 m/s/s

F=ma, so 1 kg mass (2.2 lbs at Earth’s surface) * .026 m/s/s results in a centripetal force of .026 Newtons (N), or about .006 lbs (about .096 oz. or about 1/100 of 1 oz.)

Since centrifugal force is the unbalanced reaction, the magnitude is the same, acting in the opposite direction (e.g. flinging us out toward space)

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Here is a tabular summary of all calculations in this post.

Latitude	Circumference of the Earth at that latitude - in miles	Radius of that circle in miles	Earth rotational speed in mph	Centripetal acceleration in meters/sec/sec on the Earth's surface
90°	0.0000	0.0000	0.0000	0.0000
80°	4,338.1992	690.4458	181.25	0.0059
70°	8,542.0860	1,359.5152	356.89	0.0116
60°	12,482.1049	1,986.5887	521.51	0.0170
50°	16,037.8833	2,552.5084	670.07	0.0218
40°	19,102.0618	3,040.1876	798.1	0.0260
30°	21,583.3662	3,435.0994	901.77	0.0294
20°	23,408.8865	3,725.6400	978.04	0.0319
10°	24,525.6273	3,903.3748	1,024.70	0.0334
0°	24,901.4609	3,963.1906	1,040.40	0.0339

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Latitude	Centripetal acceleration in terms of G	Centripetal acceleration percentage in terms of G	How much does 500 grams weight
90°	0.0000	0.0000	500.0000
80°	0.0006	0.0603	499.6986
70°	0.0012	0.1187	499.4064
60°	0.0017	0.1735	499.1326
50°	0.0022	0.2229	498.8855
40°	0.0027	0.2655	498.6726
30°	0.0030	0.3000	498.5002
20°	0.0033	0.3253	498.3733
10°	0.0034	0.3409	498.2957
0°	0.0035	0.3461	498.2696

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Update: March 2019

Additional experimental data as reported by Critical Think

Zero Probability: Flat Earth, by Critical Think
https://www.youtube.com/watch?v=f4o-NXUSXl8

"The Rotating Globe model explains 98% of weight change due to gravity, Flat Earth explains 0%"

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Zero Probability: Flat Earth - Part 2: The method, by Critical Think
https://www.youtube.com/watch?v=8qUQtEynaTU

The centrifugal force at point h = acceleration = vector component = 0.0294 m/sec/sec

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With reference to the data two items need to be adjusted for

1. Some of the readings were taken at different elevations above sea level. Therefore, the (weight vs latitude) relationship was adjusted to a standard height for all locations.

2. The standard weight was calibrated to be read 500-grams at different latitudes. An adjustment for this, to get all 4 locations in sync, was also made.

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Zero Probability: Flat Earth - Part 3: Error Analysis, by Critical Think
https://www.youtube.com/watch?v=5bf5EiXCmpk

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Update: March 2019

Additional experimental data as reported by Olivier Joseph

How I destroyed flat Earth idiocy (6) - Earth is not spinning?
https://www.youtube.com/watch?v=f4o-NXUSXl8