specific gravity

or relative density

Ratio of the density of a substance to that of a standard substance. For solids and liquids, the standard substance is usually water at 39.2°F (4.0°C), which has a density of 1.00 kg/liter. Gases are usually compared to dry air, which has a density of 1.29 g/liter at 32°F (0°C) and 1 atmosphere pressure. Because it is a ratio of two quantities that have the same dimensions (mass per unit volume), specific gravity has no dimension. For example, the specific gravity of liquid mercury is 13.6, because its actual density is 13.6 kg/liter, 13.6 times that of water.

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Imaginary point where the total weight of a material body may be thought to be concentrated. Since weight and mass are proportional, the same point may also be called the centre of mass, but the centre of mass does not require a gravitational field. A body's centre of gravity may coincide with its geometric centre, especially if the body is symmetric and composed of homogeneous material. In asymmetric, unhomogeneous, or hollow objects, the centre of gravity may be at some distance from the geometric centre or even at a point in space external to the object, such as between the legs of a chair.

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Gravity is a city in Taylor County, Iowa, United States. The population was 218 at the 2000 census.

Geography

Gravity is located at (40.759096, -94.744221), along the Middle Branch of the One Hundred and Two River.

According to the United States Census Bureau, the city has a total area of 0.3 square miles (0.8 km²), all of it land.

Gravity is located north of Bedford on Iowa Highway 148.

Demographics

As of the census of 2000, there were 218 people, 85 households, and 64 families residing in the city. The population density was 729.6 people per square mile (280.6/km²). There were 103 housing units at an average density of 344.7/sq mi (132.6/km²). The racial makeup of the city was 99.08% White, 0.46% Pacific Islander, 0.46% from other races. Hispanic or Latino of any race were 3.21% of the population.

There were 85 households out of which 29.4% had children under the age of 18 living with them, 60.0% were married couples living together, 11.8% had a female householder with no husband present, and 24.7% were non-families. 22.4% of all households were made up of individuals and 11.8% had someone living alone who was 65 years of age or older. The average household size was 2.56 and the average family size was 2.98.

In the city the population was spread out with 28.0% under the age of 18, 5.0% from 18 to 24, 27.1% from 25 to 44, 20.6% from 45 to 64, and 19.3% who were 65 years of age or older. The median age was 38 years. For every 100 females there were 111.7 males. For every 100 females age 18 and over, there were 98.7 males.

The median income for a household in the city was $25,000, and the median income for a family was $30,000. Males had a median income of $25,625 versus $20,536 for females. The per capita income for the city was $13,312. About 16.2% of families and 18.1% of the population were below the poverty line, including 11.8% of those under the age of eighteen and 5.4% of those sixty five or over.

References

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