05-03-2017, 08:18 PM

On Mars there IS a Datum Level.

On Earth The Meter WAS the Datum Level.

Meridional definition[edit]

In the 18th century, there were two approaches to the definition of the standard unit of length. One favoured Wilkins approach: to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth (1/10 000 000) of the length of a quadrant along the Earth's meridian; that is, the distance from the Equator to the North Pole. This means that the quadrant (a section/distance 1⁄4 of the Earth's circumference) would have been defined as exactly 10 000 000 metres (10 000 km) at that time, with the total circumference of the Earth defined as 40 000 000 metres (40 000 km). In 1791, the French Academy of Sciences selected the meridional definition over the pendular definition because the force of gravity varies slightly over the surface of the Earth, which affects the period of a pendulum.

To establish a universally accepted foundation for the definition of the metre, more accurate measurements of this meridian were needed. The French Academy of Sciences commissioned an expedition led by Jean Baptiste Joseph Delambre andPierre Méchain, lasting from 1792 to 1799, which attempted to accurately measure the distance between a belfry inDunkerque and Montjuïc castle in Barcelona to estimate the length of the meridian arc through Dunkerque. This portion of the meridian, assumed to be the same length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator. The problem with this approach is that the exact shape of the Earth is not a simple mathematical shape, such as a sphere or oblate spheroid, at the level of precision required for defining a standard of length. The irregular and particular shape of the Earth smoothed to sea level is called a geoid, which literally means "Earth-shaped", but does not correspond to the actual shape of the earth, but rather is a mathematical model of its shape. Despite these issues, in 1793 France adopted this definition of the metre as its official unit of length based on provisional results from this expedition.

33.30 gons=

33.3 grads=

29.97 degrees=

29 degrees 58 arc minutes=

523.1 mrads=

0.5231 radians

Great Pyramid of Giza set at 29:58:50.952 N = ~33.30 GONS

http://www.wolframalpha.com/input/?i=33....ual=Submit

The Great Pyramid is located at 29:58:50.952 N =~33.3 grads.

On Earth The Meter WAS the Datum Level.

Quote:The problem with this approach is that the exact shape of the Earth is not a simple mathematical shape, such as a sphere or oblate spheroid, at the level of precision required for defining a standard of length. The irregular and particular shape of the Earth smoothed to sea level is called a geoid,

Meridional definition[edit]

In the 18th century, there were two approaches to the definition of the standard unit of length. One favoured Wilkins approach: to define the metre in terms of the length of a pendulum which produced a half-period of one second. The other approach was to define the metre as one ten-millionth (1/10 000 000) of the length of a quadrant along the Earth's meridian; that is, the distance from the Equator to the North Pole. This means that the quadrant (a section/distance 1⁄4 of the Earth's circumference) would have been defined as exactly 10 000 000 metres (10 000 km) at that time, with the total circumference of the Earth defined as 40 000 000 metres (40 000 km). In 1791, the French Academy of Sciences selected the meridional definition over the pendular definition because the force of gravity varies slightly over the surface of the Earth, which affects the period of a pendulum.

To establish a universally accepted foundation for the definition of the metre, more accurate measurements of this meridian were needed. The French Academy of Sciences commissioned an expedition led by Jean Baptiste Joseph Delambre andPierre Méchain, lasting from 1792 to 1799, which attempted to accurately measure the distance between a belfry inDunkerque and Montjuïc castle in Barcelona to estimate the length of the meridian arc through Dunkerque. This portion of the meridian, assumed to be the same length as the Paris meridian, was to serve as the basis for the length of the half meridian connecting the North Pole with the Equator. The problem with this approach is that the exact shape of the Earth is not a simple mathematical shape, such as a sphere or oblate spheroid, at the level of precision required for defining a standard of length. The irregular and particular shape of the Earth smoothed to sea level is called a geoid, which literally means "Earth-shaped", but does not correspond to the actual shape of the earth, but rather is a mathematical model of its shape. Despite these issues, in 1793 France adopted this definition of the metre as its official unit of length based on provisional results from this expedition.

Quote:What is the relation between radian, degree and grad?

Posted by Ancient Vizier - Today, 01:46 am

Quote:Okay... Can I give you a Ted Talk on finding ways to

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2 Answers

[url=https://www.quora.com/profile/Sachin-Maurya-4]

Sachin Maurya, works at Accenture

Written 21 Jun 2015

1 degree = 1/360 of a circle

1 radian = 1/(2pi) of a circle

1 gradient = 1/400 of a circle (and is much less used than the others)

1/400 of a datum Circle is 90 degrees or the Distance of the North Pole to Equator along any Prime Meridian.(where you derive your meter from naturally)

Degrees and gradients are arbitrarily chosen using convenient divisors (360 and 400).

1 radian = the angle created when the radius of a circle is laid out along the circumference.

Since C = 2 pi r, there are 2 pi radians in a full circle.

1 radian = about 57.3 degrees = 63.66 grads.

So question arises is :-

Why does anyone want to divide a right angle into 100 grads instead of 90 degrees?

grads are a decimal unit, and are subdivided into simple 100ths, just like the meter is subdivided into cetimeters..Degrees are not decimal units--they are subdivided into 60 minutes and then another 60 Page on seconds.so every time you want to do a simple calculation (say, adding two angles), you have to do first do TWO extra steps--convert the seconds into decimal minutes, then convert the decimalized minutes into decimal degrees. (most pocket calculators have a simple button that does this, but it still requires you to press an extra button before doing the actual calculation that you want to complete.

try this example--add two angles : 75 degrees, 45 minutes, 20 seconds plus 25 degrees 15 minutes 10 seconds.

or add 75.753 plus 25.251

Which is easier?

Land surveyors (those guys you see on the side of the road with an instrument mounted on a tripod) make hundreds or even thousands of angle measurements during a day's work.

Grads are great!!! :)

33.30 gons=

33.3 grads=

29.97 degrees=

29 degrees 58 arc minutes=

523.1 mrads=

0.5231 radians

Great Pyramid of Giza set at 29:58:50.952 N = ~33.30 GONS

http://www.wolframalpha.com/input/?i=33....ual=Submit

The Great Pyramid is located at 29:58:50.952 N =~33.3 grads.

Along the vines of the Vineyard.

With a forked tongue the snake singsss...

With a forked tongue the snake singsss...