Earth Gravity: The Gravitational Acceleration Structure

Earth  Gravity:  The Gravitational Acceleration Structure

  • The earth’s gravity, denoted by G, refers to the acceleration that the earth gives to its surface or the objects around it.
  • In SI units this acceleration is denoted as equivalent per square meter (in symbols, m / s2) or Newton per kg (n / kg). 
  • It has a calculated value of (9.81 m / s2) which means ignoring the effects of wind resistance, The speed of an object that falls freely near the surface of the earth will increase by about 9.81 meters (32.2 feet) per second.
  • This amount is sometimes informally referred to as the small G (in contrast, the gravitational constant GT is referred to as the Big G).
  • Gravitational acceleration is directly related to the downward force (weight) seen by objects on earth, which gives the equation F = ma (energy = mass × acceleration).
  • However, other factors such as the rotation of the earth contribute to net acceleration.
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Fig. 1: Gravitational acceleration of Earth

Earth’s gravitational

  • Earth’s gravitational pull varies depending on where it is located. By terms, the nominal “average” range of the Earth’s layer, known as the standard gravity, is 9.80665 m / s2 (approximately 32.1740 tr / s2). 
  • This quantity is expressed separately as gn, ge (although it is sometimes expressed as the Earth’s normal equatorial value, 9.78033 m / s2), g0, gee, or simply G (also used for variable local values).
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Fig no.2: Diagram of Earth’s gravitational and its structure.

Variation on Gravity:

  • A rotating right sphere of equal density, or whose density changes depending on the distance from the center (spherical symmetry), can form a gravitational field of equal magnitude at all points on its surface.
  • The earth rotates and is not spherical; Instead, when it’s stirred in the Mediterranean, something is flattering at the poles: an oxygen pill.
  • The result is a slight deviation in the shape of gravity on its surface.


  • Differences in the gravity of the earth around the continent of Antarctica.
  • A clear gravity is as weak as near the equator because the rotation of the earth produces a clear focal force. T
  • The second major reason for the difference in gravity individually is that the Earth’s equatorial bulge forms objects in the equatorial region more in the center of the planet than objects in the poles.


  • The gravitational pull decreases in height when it rises above the surface of the earth because the altitude represents a distance from the center of the earth.
  • All things being equal, an increase in altitude of 9,000 meters (30,000 feet) above sea level will result in a weight loss of 0.29% (Another factor that affects the apparent weight is a decrease in air density, which reduces the quality of the product.
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Fig. 4: show the latitude and altitude of the world

Local Topography and Geology:

  • Geological differences in terrain (such as the presence of mountains), geology (such as the density of rocks in the area), and the depth of technical structure cause local and regional variations in gravitational anomalies, known as gravitational anomalies. Some of these problems can be very large, resulting from noise at sea level, and throwing pendulum hours into alignment.
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Fig. 5: Show the geological topographic variation

The Earth’s magnetic: 

  • Earth’s magnetic field tilts 11 degrees from the Earth’s axis of rotation like a rod magnet. The problem with this picture is that the Curie Iron temperature is around 770 celsius.
  • The earth’s core is warmer than it is and therefore not magnetic. Magnetic fields revolve around electric currents, so we assume that the electric currents in the earth’s molten metal core are the beginning of the magnetic field.
  • An existing loop provides an area equal to the ground. The magnitude of the magnetic field measured on the Earth’s surface is half that of Gauss and sinks toward the Earth in the northern gold fire.
  • Sizes range from 0.3 to 0.6 Gauss above the Earth’s surface.
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Thermal Structure:

  • Surface heat flux can be divided into two main parts. The first part is about the radioactive heat sources in the upper crust, and the second part is about the lower crust and upper screen sources.
  • Heat flux from the lower and upper crusts is more stable than large areas, known as heat flow provinces, and the transition between states is very narrow (less than 100 km).
  • Occurrences occur in high heat flow values ​​(> 1.4 μcal / cm2 sec). as we know that the earth’s totals heat loss is 4.2*10^13 watts.
  • A portion of the core thermal energy is transported towards the crust by mantle plumes.
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