  A complete theoretical study is presented for the disappearance of flow, for
the first time, by analyzing 15 reactions with masses between 47 and 476 units.
We demonstrate that the effect of nucleon-nucleon cross-section reduces to
insignificant level for heavier colliding nuclei in agreement with previous
studies. A stiff equation of state with nucleon-nucleon cross-sections of 35-40
mb is able to explain all the measured balance energies within few percent. A
power law is also given for the mass dependence of the disappearance of flow
which is in excellent agreement with experimental data.
