Earth radius – wikipedia electricity quiz ks3


Earth radius is the distance from a selected center of Earth to a point on its surface, which is often chosen to be sea level, or more commonly, the surface of an idealized ellipsoid representing the shape of Earth. Because Earth is not a perfect sphere, the determination of Earth’s radius can have several values, depending on how it is measured; from its equatorial radius of about 6,378 kilometres (3,963 miles) to its polar radius grade 6 electricity experiments of about 6,357 kilometres (3,950 miles).

The International Union of Geodesy and Geophysics (IUGG) gives three global average radii, the gas ninjas arithmetic mean of the radii of the ellipsoid (R 1), the radius of a sphere with the same surface area as the ellipsoid or authalic radius (R 2), and the radius of a sphere with the same volume as the ellipsoid (R 3). [2] All three IUGG average radii are about 6,371 kilometres (3,959 mi). A fourth global average radius not mentioned by the electricity per kwh IUGG is the rectifying radius, the radius of a sphere with a circumference equal to the perimeter of the polar cross section of the ellipsoid, about 6,367 kilometres (3,956 mi). The radius of curvature at any point on the surface of the ellipsoid depends on its coordinates and its azimuth, north-south (meridional), east-west (prime vertical), or somewhere in between.

Earth’s rotation, internal density variations, and external tidal forces cause its shape to deviate systematically from a perfect sphere. [a] Local topography increases the variance, resulting in a surface of profound complexity. Our descriptions of Earth’s surface gas tracker must be simpler than reality in order to be tractable. Hence, we create models to approximate characteristics of Earth’s surface, generally relying on the simplest model that suits the need.

Each of the models in common use involve some notion of the geometric radius. Strictly speaking, spheres are the only solids to have radii, but broader uses of the term radius are common in many fields, including those dealing with models of Earth. The following is a partial list of models of Earth’s surface electricity physics pdf, ordered from exact to more approximate:

In the case of the geoid and ellipsoids, the fixed distance from any point on the model to the specified center is called a radius of the Earth or the radius of the Earth gas station near me at that point. [d] It is also common to refer to any mean radius of a spherical model as the radius of the earth. When considering the Earth’s real surface, on the other hand, it is uncommon to refer to a radius, since there is generally no practical need. Rather, elevation above or below sea level is useful.

Regardless of the model, any radius falls between the polar minimum of about 6,357 km and the equatorial maximum of about 6,378 km (3,950 to 3,963 mi). Hence, the Earth deviates from a perfect sphere by only a third of a percent, which supports the spherical model in many contexts and justifies the term radius of the Earth. While specific values differ, the concepts in this article generalize to any major planet bp gas locations.

where ω is the angular frequency, G is the gravitational constant, and M is the mass of the planet. [e] For the Earth 1 / q ≈ 289, which is close to the measured inverse flattening 1 / f ≈ 298.257. Additionally, the bulge at the equator shows slow variations. The bulge had been decreasing, but since 1998 the bulge gas 66 has increased, possibly due to redistribution of ocean mass via currents. [4]

Additionally, the radius can be estimated from the curvature of the Earth at a point. Like a torus, the curvature at a point will be greatest (tightest) in one direction (north–south on Earth) and smallest (flattest) perpendicularly (east–west). The corresponding radius of curvature depends on the location and direction of measurement from that point. A consequence is that electricity review worksheet answers a distance to the true horizon at the equator is slightly shorter in the north/south direction than in the east-west direction.

In summary, local variations in terrain prevent defining a single precise radius. One can only adopt an idealized model. Since the estimate by Eratosthenes, many models have been created. Historically, these models electricity in human body wiki were based on regional topography, giving the best reference ellipsoid for the area under survey. As satellite remote sensing and especially the Global Positioning System gained importance, true global models were developed which, while not as accurate for regional work, best approximate the Earth as a whole.

The radii in this section are for an idealized surface. Even the idealized radii have an uncertainty of ±2 m. [7] The discrepancy between the ellipsoid radius and the radius to a physical location may be significant. When identifying the position of an observable location, the use of more precise values for WGS-84 radii may not yield a corresponding improvement in accuracy.

Most global mean radii electricity office are based on the reference ellipsoid, which approximates the geoid. The geoid has no direct relationship with surface topography gas stoichiometry problems, however. An alternative calculation averages elevations everywhere, resulting in a mean radius 7002230000000000000♠230 m larger than the IUGG mean radius, the authalic radius, or the volumetric radius. This average is 6,371.230 km (3,958.899 mi) with uncertainty of 10 m (33 ft). [13] Osculating sphere [ edit ]

The best local spherical approximation to the ellipsoid in the vicinity of a given point is the osculating sphere. Its radius equals the gas nozzle prank Gaussian radius of curvature as above, and its radial direction coincides with the ellipsoid normal direction. The center of the osculating sphere is offset from the center of the ellipsoid, but is at the center of curvature for the given point on the ellipsoid surface. This concept aids the interpretation of terrestrial and planetary radio occultation refraction measurements and in some navigation and surveillance applications. [14] [15] Published values [ edit ]