specific gravity (redirected from relative density)

gravity /grav·i·ty/ (grav´it-e)

1. the phenomenon by which two bodies having mass are attracted to each other.

2. the gravitational attraction near a large body having mass, particularly near or on the surface of a planet or star.

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specific gravity  the ratio of the density of a substance to that of a reference substance at a specified temperature.

standard gravity  (g ) the acceleration due to gravity at mean sea level on earth, 9.80616 meters per second squared.

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specific gravity

n. Abbr. sg, sp gr

The ratio of the mass of a solid or liquid to the mass of an equal volume of distilled water at 4°C (39°F) or of a gas to an equal volume of air or hydrogen under prescribed conditions of temperature and pressure.

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specific gravity (sp. gr.),

the ratio of the density of a substance to the density of another substance accepted as a standard. The usual standard for liquids and solids is water. Thus a liquid or solid with a specific gravity of 4 is four times as dense as water at the same temperature. Hydrogen is the usual standard for gases. See also density, mass.

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specific gravity (SG),

n a measurement calculated by dividing the mass of the desired volume of a substance by the mass of an equivalent volume of water. Both measurements must be taken under identical pressure and temperature conditions. Used to determine the presence of impurities within an essential oil. Also used in diagnostic analysis of fluids such as urine.

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specific gravity,

n See gravity, specific.

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specific gravity

Lab medicine A measure of the solutes in a fluid; SG is detected in the urine, based on the response of a polymeric acid to surrounding ions. See Dipstick. Cf Nitrites Nephrology The SG reflects the kidney's ability to concentrate urine: if a random urine specimen has an SG > 1.023, the kidney's ability to concentrate is assumed to be normal ; SG ↑ in SIADH, uncontrolled DM, proteinuria, eclampsia and obstructive uropathy and ↓ in renal tubular damage, chronic renal insufficiency, diabetes insipidus, malignant HTN Occupational safety A physical parameter of a liquid that indicates how heavy it is in relationship to air–≤ 1.0 = lighter than water; ≥ 1.0 = heavier than water, a datum of interest to OSHA, which requires listing of SGs in its Materials Safety Data Sheets