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Surprisingly, the answer is 2 π m or around 6.3 metres (21 ft). In the second phrasing, considering that 1 metre (3 ft 3 in) is almost negligible compared with the 40,000 km (25,000 mi) circumference, the first response may be that the new position of the string will be no different from the original surface-hugging position.
Earth radius (denoted as R 🜨 or R E) is the distance from the center of Earth to a point on or near its surface. Approximating the figure of Earth by an Earth spheroid (an oblate ellipsoid), the radius ranges from a maximum (equatorial radius, denoted a) of nearly 6,378 km (3,963 mi) to a minimum (polar radius, denoted b) of nearly 6,357 km (3,950 mi).
[The percentage error, which increases roughly in proportion to the height, is less than 1% when H is less than 250 km.] With this calculation, the horizon for a radar at a 1-mile (1.6 km) altitude is 89-mile (143 km). The radar horizon with an antenna height of 75 feet (23 m) over the ocean is 10-mile (16 km).
where h is height above sea level and R is the Earth radius. The expression can be simplified as: , where the constant equals k= 3.57 km/m ½ = 1.22 mi/ft ½. In this equation, Earth's surface is assumed to be perfectly spherical, with R equal to about 6,371 kilometres (3,959 mi).
= 6,371.009 kilometers = 3,958.761 statute miles = 3,440.069 nautical miles. = Distance between the two points, as measured along the surface of the Earth and in the same units as the value used for radius unless specified otherwise.
Near the surface of the Earth, the acceleration due to gravity g = 9.807 m/s 2 (metres per second squared, which might be thought of as "metres per second, per second"; or 32.18 ft/s 2 as "feet per second per second") approximately. A coherent set of units for g, d, t and v is essential.
Posidonius calculated the Earth's circumference by reference to the position of the star Canopus.As explained by Cleomedes, Posidonius observed Canopus on but never above the horizon at Rhodes, while at Alexandria he saw it ascend as far as 7 + 1 ⁄ 2 degrees above the horizon (the meridian arc between the latitude of the two locales is actually 5 degrees 14 minutes).
Geopotential height differs from geometric height (as given by a tape measure) because Earth's gravity is not constant, varying markedly with altitude and latitude; thus, a 1-m geopotential height difference implies a different vertical distance in physical space: "the unit-mass must be lifted higher at the equator than at the pole, if the same ...