# The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2

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#### kabu

##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« on: February 16, 2007, 05:58:11 PM »
This thread is in response to the thread about relativity.  I feel that a great many people are laboring under some misconceptions, so this post merits its own thread.  I am not trying to say anything about the flatness/roundness of the Earth in this thread, but I cannot tolerate <b>provable</b> scientific fact being misinterpreted in such a fashion.

The Earth is NOT accelerating at 32 ft/s^2.

This is the acceleration that an object will undergo when dropped from a height relatively near (say, within a hundred kilometers) the Earth's surface.  This is true whether or not you believe in flat Earth, anyone with a couple of rocks, a three story high building, and a stopwatch can verify for themselves (as I did, repeatedly, in many physics courses through my educational career).  Once again, this is a concrete, easily demonstrated fact that cannot be used one way or another for the Flat/Round Earth Theory.  The number 32 ft/s^2 (or 9.8 m/s, for Europeans) has absolutely nothing to do with the speed or acceleration <b>of</b> the Earth, but rather the acceleration of objects on the Earth.

In the metric system, the force (measured in Newtons) of Gravity acting on an object near Earth's surface is equal to 9.8 m/s * the mass in kilograms.  This is not something that I have heard about, or have been told, but something that I have directly observed many times.

In summary:  The number 9.81 m/s or 32.19 ft/s^2 has absolutely nothing to due with the speed, acceleration, or whatnot of the Earth.  It has to due with the acceleration of objects on or near the Earth's surface.

To reiterate:  I am not saying anything about round vs. flat Earth here.  I am simply pointy out a fallacious argument based on a misinterpretation of an easily provable, demonstrable, and scientifically sound fact that is believed by Flat Earthers, Round Earthers, Hollow Earthers, and any other version of Earth that humans have cared to believe in over the course of recorded history.

The version of relativity presented in the above mentioned thread also has some flaws in its interpretation of relativity.  I feel that it would do both round and flat Earth proponents some good to actually familiarize themselves with a topic before discussing it.

General Relativity, which explains frames of reference (and that even if the earth were accelerating at any imaginable speed, we (along with our satellites, &c.) would be unaware because we share a common inertial frame of reference, and Special Relativity, which has nothing to do with the topic but is pretty darn interesting by itself.

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#### EnragedPenguin

• The Elder Ones
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##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« Reply #1 on: February 16, 2007, 06:01:41 PM »
According to the equivalence principal, there is no difference locally between being in a gravitational field and being on an accelerating platform.
A different world cannot be built by indifferent people.

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#### kabu

##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« Reply #2 on: February 16, 2007, 06:06:11 PM »
Quote from: "EnragedPenguin"
According to the equivalence principal, there is no difference locally between being in a gravitational field and being on an accelerating platform.

Exactly.  That is perfectly correct.

I am not using this fact to prove/disprove any Round Earth/ Flat Earth theory, merely to point out a fallacy that some people are quoting as fact, that the Earth is accelerating at any given speed.  This is a fact that can be easily accepted by Round Earth or Flat Earth (or even Hollow Earth) enthusiasts.

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#### EnragedPenguin

• The Elder Ones
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##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« Reply #3 on: February 16, 2007, 06:11:05 PM »
Quote from: "kabu"
I am not using this fact to prove/disprove any Round Earth/ Flat Earth theory, merely to point out a fallacy that some people are quoting as fact, that the Earth is accelerating at any given speed.

It's not a fallacy. According to the flat Earth theory, the effects of gravity are produced by Earth accelerating "upwards" at 1g.
""There is no difference locally between being in a gravitational field and being on an accelerating platform" meaning that someone on Earth cannot tell if they are accelerating towards the ground when they jump, or if the ground is accelerating towards them.
A different world cannot be built by indifferent people.

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#### matt2

##### Units Correction
« Reply #4 on: February 16, 2007, 06:36:29 PM »
A correction to the units mentioned above:

ft/s denotes velocity not acceleration, acceleration is in ft/(s*s)

Gravity near the earth's surface is actually 32 ft/(s*s) or 32 feet per second per second. So if the earth is accelerating upwards, then it is gaining speed at the rate of 32 feet per second, every second. Just so you know, we hit light speed only several thousand years after the earth was formed, gosh I hope we don't hit something...

#### TheEngineer

• Planar Moderator
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• GPS does not require satellites.
##### Re: Units Correction
« Reply #5 on: February 16, 2007, 06:38:34 PM »
Quote from: "matt2"
Just so you know, we hit light speed only several thousand years after the earth was formed, gosh I hope we don't hit something...

Einstein says you're wrong.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson

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#### kabu

##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« Reply #6 on: February 16, 2007, 06:44:19 PM »
Then why is it that the effects of gravity are measurably different at different latitudes and altitudes?

The explanation that I find most acceptable (again, if you disagree feel free to say so) is that the force of gravity is proportional to the distance from the center of mass, so at extreme North or South latitudes the force of gravity is slightly less (given that Earth is in the shape of a near-spherical ellipsoid, and is "squished" at the poles as detailed in this thread ), as well as being slightly less at the tops of high mountains (for example, in Denver, Colorado).  The measured differences in weight (which is the same as the force of gravity, or the Normal Force for a Flat Earth believer) at different altitudes can be verified by anyone with a good stopwatch, an aerodynamic projectile and a high drop.

Everywhere that gravity has been measured on or above Earth, it has followed Newton's (way before NASA) equation of universal gravitation, namely

Force due to gravity on an object = (M1*M2*G)/(r^2)

where M1 and M2 are the masses (in kilograms) of two objects (say, the Earth and a ball, or two metal spheres), G is the fine gravitational constant (approximately 6.67 × 10^-11 m^3/kg s^2), and r is the distance between the centers of the two objects.

Incidentally, these equations work even when the mass and radius of the Earth (which many Flat Earth believers hold to be false, which is something that I cannot disprove).  In fact, the gravitational constant was first verified by Henry Cavendish in the 1700's, long before NASA, using two metal balls of known mass and radius, some string, and a long thin beam without using the mass or radius of the Earth at all.  His results were later used to calculate the value of G to many accurate decimal places.  This should show to any Flat Earth or Round Earth believer that Newton's equation is accurate, and can easily explain the effect of altitude on gravity.

For a demonstration of the Cavendish balance, visit this webpage.  The masses M and m are attracted to each other, and their deflection is measured by a reflected beam of light.  Cavendish was careful to isolate the effects of heat, air, magnetism and any other variables.  Anyone with some time on their hands could replicate his experiment.

And once again, may I refer readers of this post to Ockham's razor.

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#### kabu

##### Re: Units Correction
« Reply #7 on: February 16, 2007, 06:45:26 PM »
Quote from: "matt2"
A correction to the units mentioned above:

ft/s denotes velocity not acceleration, acceleration is in ft/(s*s)

Gravity near the earth's surface is actually 32 ft/(s*s) or 32 feet per second per second. So if the earth is accelerating upwards, then it is gaining speed at the rate of 32 feet per second, every second. Just so you know, we hit light speed only several thousand years after the earth was formed, gosh I hope we don't hit something...

You're right, those were just stupid typos.  I'll correct them.

Thank you.

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#### matt2

##### Light Speed
« Reply #8 on: February 16, 2007, 06:52:43 PM »
[Einstein says you're wrong.]

True, my calculations had a unit error in them, guess I'm not immune to that one either. We hit light speed in about a year actually. And I suppose he also said that one can't reach the speed of light or the entire universe would implode, but if we were to suspend reality for a short time, we can look to the great movie "Spaceballs" for guidance. They say it is possible to reach reach Ludicrous Speed, which is just past Ridiculous Speed, which is even faster than the speed of light.

#### TheEngineer

• Planar Moderator
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• GPS does not require satellites.
##### Re: Light Speed
« Reply #9 on: February 16, 2007, 07:41:27 PM »
Quote from: "matt2"
[Einstein says you're wrong.]

True, my calculations had a unit error in them, guess I'm not immune to that one either. We hit light speed in about a year actually. And I suppose he also said that one can't reach the speed of light or the entire universe would implode, but if we were to suspend reality for a short time, we can look to the great movie "Spaceballs" for guidance. They say it is possible to reach reach Ludicrous Speed, which is just past Ridiculous Speed, which is even faster than the speed of light.

Einstein still says you're wrong.  Velocities don't add linearly in relativity.  An object undergoing constant acceleration will never reach the speed of light.  It's all in the math.

"I haven't been wrong since 1961, when I thought I made a mistake."
-- Bob Hudson

#### Dioptimus Drime

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• Meep.
##### The Earth is NOT accelerating at 9.8 m/s^2 or 32 ft/s^2
« Reply #10 on: February 16, 2007, 08:42:08 PM »
Seeing as nobody took this, and you're still wrong on relativity, I'll take my time to rant at you about this:

Quote from: "kabu"
And once again, may I refer readers of this post to Ockham's razor.

Occam's razor does not apply in this debate. At all.
A) Just because something makes mroe assumptions doesn't mean it necessitates its truthfulness. It's perhaps more LIKELY, but that doesn't mean it's entirely inherent.
B) Occam's razor is only applied when both theories are technically the same in the ways of evidence. For example, if presented with two examples for the mechanic of global warming, one would (and SHOULD) be much more inclined to believe that it's due to the atmosphere trapping in greenhouse gases than a flurry of invisible, pink unicorns who are trampling over all of our coldness. The latter is simply assuming far too much, and this is what Occam's razor is saying. To make as few assumptions as possible.
However, it in no way is a way of logically proving a point. It's just a matter of what is more likely. Both theories as is are just as likely. If you disagree, you obviously haven't read too much into the flat Earth theory yet.

~D-Draw