“earth”的概念、定义、翻译、参考文献-科学参考

earth

Physics

The planet that orbits the sun between the planets Venus and Mars at a mean distance from the sun of 149 600 000 km. It has a mass of about 5.974×10²⁴ kg and an equatorial diameter of 12 756 km. The earth consists of three layers: the gaseous atmosphere (see earth’s atmosphere), the liquid hydrosphere, and the solid lithosphere. The solid part of the earth also consists of three layers: the crust with a mean thickness of about 32 km under the land and 10 km under the seas; the mantle, which extends some 2900 km below the crust; and the core, part of which is believed to be liquid. The crust has a relative density of about 3 and consists largely of sedimentary rocks overlaying igneous rocks. The composition of the crust is: oxygen 47%, silicon 28%, aluminium 8%, iron 4.5%, calcium 3.5%, sodium and potassium 2.5% each, and magnesium 2.2%. Hydrogen, carbon, phosphorus, and sulphur are all present to an extent of less than 1%. The mantle reaches a relative density of about 5.5 at its maximum depth and is believed to consist mainly of silicate rocks. The core is believed to have a maximum relative density of 13 and a maximum temperature of 6400 K. See also geomagnetism; geophysics.

Chemistry

The planet that orbits the sun between the planets Venus and Mars. The earth consists of three layers: the gaseous atmosphere (see earth’s atmosphere), the liquid hydrosphere, and the solid lithosphere. The solid part of the earth also consists of three layers: the crust with a mean thickness of about 32 km under the land and 10 km under the seas; the mantle, which extends some 2900 km below the crust; and the core, part of which is believed to be liquid. The composition of the crust is: oxygen 47%, silicon 28%, aluminium 8%, iron 4.5%, calcium 3.5%, sodium and potassium 2.5% each, and magnesium 2.2%. Hydrogen, carbon, phosphorus, and sulphur are all present to an extent of less than 1%.

Electronics and Electrical Engineering

1. A large conducting body, such as the earth, that is taken to be the arbitrary zero in the scale of electric potential.
2. A connection, which may be accidental, between a conductor and the earth. An effective earth for electrical equipment is formed by a wire connected to a cold water pipe. Connection may also be made to an earth electrode, i.e. a large copper plate buried in moist soil.
3. The point or portion in an electric circuit or device that is at zero potential with respect to earth.
4. To connect an electric circuit or device to earth.

单词	earth
释义	earth Physics The planet that orbits the sun between the planets Venus and Mars at a mean distance from the sun of 149 600 000 km. It has a mass of about 5.974×10²⁴ kg and an equatorial diameter of 12 756 km. The earth consists of three layers: the gaseous atmosphere (see earth’s atmosphere), the liquid hydrosphere, and the solid lithosphere. The solid part of the earth also consists of three layers: the crust with a mean thickness of about 32 km under the land and 10 km under the seas; the mantle, which extends some 2900 km below the crust; and the core, part of which is believed to be liquid. The crust has a relative density of about 3 and consists largely of sedimentary rocks overlaying igneous rocks. The composition of the crust is: oxygen 47%, silicon 28%, aluminium 8%, iron 4.5%, calcium 3.5%, sodium and potassium 2.5% each, and magnesium 2.2%. Hydrogen, carbon, phosphorus, and sulphur are all present to an extent of less than 1%. The mantle reaches a relative density of about 5.5 at its maximum depth and is believed to consist mainly of silicate rocks. The core is believed to have a maximum relative density of 13 and a maximum temperature of 6400 K. See also geomagnetism; geophysics. Chemistry The planet that orbits the sun between the planets Venus and Mars. The earth consists of three layers: the gaseous atmosphere (see earth’s atmosphere), the liquid hydrosphere, and the solid lithosphere. The solid part of the earth also consists of three layers: the crust with a mean thickness of about 32 km under the land and 10 km under the seas; the mantle, which extends some 2900 km below the crust; and the core, part of which is believed to be liquid. The composition of the crust is: oxygen 47%, silicon 28%, aluminium 8%, iron 4.5%, calcium 3.5%, sodium and potassium 2.5% each, and magnesium 2.2%. Hydrogen, carbon, phosphorus, and sulphur are all present to an extent of less than 1%. Electronics and Electrical Engineering 1. A large conducting body, such as the earth, that is taken to be the arbitrary zero in the scale of electric potential. 2. A connection, which may be accidental, between a conductor and the earth. An effective earth for electrical equipment is formed by a wire connected to a cold water pipe. Connection may also be made to an earth electrode, i.e. a large copper plate buried in moist soil. 3. The point or portion in an electric circuit or device that is at zero potential with respect to earth. 4. To connect an electric circuit or device to earth.
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