  It is shown that, in the two brane time variation model framework, if the
hidden brane tension varies according to the phenomenological Eotvos law, the
visible brane tension behavior is such that its time derivative is negative in
the past and positive after a specific time of cosmological evolution. This
behavior is interpreted in terms of an useful mechanical system analog and its
relation with the variation of the Newtonian (effective) gravitational
`constant' is explored.
