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Entity > Abstract > Quantity > PhysicalQuantity > ConstantQuantity > SolidAngleMeasure > Steradian
Up: SolidAngleMeasure, SystemeInternationalUnit

Steradian
subjectfact 
Steradiandocumentation SI SolidAngleMeasure. Symbol: sr. It is 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. Another definition is: the solid angle which, having its vertex in the center of the sphere, cuts off an area of the surface of the sphere equal to that of a square with sides of length equal to the radius of the sphere. Steradian = m^2/m^2 = 12001-11-30 13:35:19.0
is an instance of SolidAngleMeasure2001-11-30 13:35:19.0
is an instance of SystemeInternationalUnit2001-11-30 13:35:19.0
ConstantQuantityhas axiom 
(=>
    (instance ?FUNCTION UnaryConstantFunctionQuantity)
    (and
       (domain ?FUNCTION 1 ConstantQuantity)
       (range ?FUNCTION ConstantQuantity)))
2001-11-30 13:33:55.0
is first domain of MagnitudeFn2001-11-30 13:33:55.0
is second domain of measure2001-11-30 13:33:55.0
UnitOfMeasurehas axiom 
(=>
    (and
       (equal (MeasureFn ?NUMBER ?UNIT) ?QUANT)
       (subclass ?UNIT ?QUANTTYPE)
       (not (equal ?QUANTTYPE UnitOfMeasure)))
    (subclass ?QUANT ?QUANTTYPE))
2001-11-30 13:35:31.0
has axiom 
(=>
    (and
       (instance ?FUNCTION RelationExtendedToQuantities)
       (instance ?FUNCTION BinaryFunction)
       (instance ?NUMBER1 RealNumber)
       (instance ?NUMBER2 RealNumber)
       (equal (AssignmentFn ?FUNCTION ?NUMBER1 ?NUMBER2) ?VALUE))
    (forall (?UNIT)
       (=>
          (instance ?UNIT UnitOfMeasure)
          (equal (AssignmentFn ?FUNCTION 
                    (MeasureFn ?NUMBER1 ?UNIT) 
                    (MeasureFn ?NUMBER2 ?UNIT)) 
                 (MeasureFn ?VALUE ?UNIT)))))
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has axiom 
(=>
    (and
       (instance ?REL RelationExtendedToQuantities)
       (instance ?REL BinaryRelation)
       (instance ?NUMBER1 RealNumber)
       (instance ?NUMBER2 RealNumber)
       (holds ?REL ?NUMBER1 ?NUMBER2))
    (forall (?UNIT)
       (=>
          (instance ?UNIT UnitOfMeasure)
          (holds ?REL (MeasureFn ?NUMBER1 ?UNIT) (MeasureFn ?NUMBER2 ?UNIT)))))
2001-11-30 13:35:31.0
is second domain of MeasureFn2001-11-30 13:35:31.0
PhysicalQuantityis partitioned into ConstantQuantity, FunctionQuantity2001-11-30 13:34:58.0
Abstractis disjoint from Physical2001-11-30 13:33:32.0