| sr1 | |
| —symbol for | |
| steradian | |
| sr2 | |
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| Suriname | |
| Sr | |
| —abbreviation for | |
| 1. | (after a name) senior |
| 2. | Señor |
| 3. | Sir |
| 4. | Sister (religious) |
| —the chemical symbol for | |
| 5. | strontium |
Sr
The symbol for the element strontium.
| Sr
The symbol for strontium. |
| strontium (strŏn'chē-əm, -tē-əm) Pronunciation Key
Symbol Sr A soft, silvery metallic element of the alkaline-earth group that occurs naturally only as a sulfate or carbonate. One of its isotopes is used in the radiometric dating of rocks. Because strontium salts burn with a red flame, they are used to make fireworks and signal flares. Atomic number 38; atomic weight 87.62; melting point 769°C; boiling point 1,384°C; specific gravity 2.54; valence 2. See Periodic Table. |
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sr
unit of solid-angle measure in the International System of Units (SI), defined as the solid angle of a sphere subtended by a portion of the surface whose area is equal to the square of the sphere's radius. Since the complete surface area of a sphere is 4pi times the square of its radius, the total solid angle about a point is equal to 4pi steradians. Derived from the Greek for solid and the English word radian, a steradian is, in effect, a solid radian; the radian is an SI unit of plane-angle measurement defined as the angle of a circle subtended by an arc equal in length to the circle's radius
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