The virial theorem states that the total kinetic energy of the objects in a
spherical, self-gravitating, stable assembly is equal to negative 1/2 times the total gravitational potential energy, if the objects can be assumed to have equal masses.
... them, 48.7% are married couples living together, 20.9% have a female householder with no husband present, and 23.4% are non-families. 20.3% of all households are made up ...