an abstract class of model fragments whose sole purpose is to have the gravitational acceleration due to earth.
the gravitational acceleration on earth
(Forall (?Self ?Time)
(=> (Active ?Time Earth-Bound-Model ?Self)
(= (Lambda (?T)
(If (= ?T ?Time)
(Value-At (Acceleration-Due-To-Gravity ?Self)
?T)))
9.81)))
(Forall (?Self ?Time)
(<=> (Active ?Time Earth-Bound-Model ?Self)
(Earth-Bound-Model ?Self)))
(=> (Earth-Bound-Model ?Self)
(Quantity.Dimension (Acceleration-Due-To-Gravity ?Self)
Acceleration-Dimension))