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Eotvos (unit)
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Eotvos (unit)

The eotvos is a unit of acceleration divided by distance. The eotvos is defined as 1/1,000,000,000 galileo per centimetre. In SI units, one eotvos equals 1/1,000,000,000 1/second2. The symbol of the eotvos unit is E.

The gravitational gradient of the Earth, that is, the change in gravitational acceleration from one point on the Earth's surface to another, is customarily measured in units of eotvos.

The largest component of the Earth's gravitational gradient is in the vertical direction, and measures about 3000 eotvos (an elevation increase of 1 m gives a decrease of gravity of 0.3 mgal).

The horizontal components are much less. At mid-latitudes in flat homogeneous terrain it is ca. 8 eotvos (moving in the direction of the nearest pole gives an increase of gravity of 0.8 mgal per km) due to the flattening of the Earth at the poles and the centrifugal force of Earth's rotation.

Gradient anomalies in mountainous areas are in the neighborhood of 1000 eotvos.

The eotvos unit is named for the physicist Roland Eötvös, who made pioneering studies of the gradient of the Earth's gravitational field.