About: http://webisa.webdatacommons.org/322890240

Property	Value
http://www.w3.org/1999/02/22-rdf-syntax-ns#type	http://www.w3.org/ns/prov#Entity
http://www.w3.org/ns/prov#value	There the full 3D analytical solution is given for the gravitation of an annulus with area density (sigma) varying inversely with the radius R, so sigma = k/R where k is a constant.
http://www.w3.org/ns/prov#wasQuotedFrom	physicsworld.com