Azimuthal distributions of radial (transverse) momentum, mean radial
momentum, and mean radial velocity of final state particles are suggested for
relativistic heavy ion collisions. Using transport model AMPT with string
melting, these distributions for Au + Au collisions at 200 GeV are presented
and studied. It is demonstrated that the distribution of total radial momentum
is more sensitive to the anisotropic expansion, as the anisotropies of final
state particles and their associated transverse momentums are both counted in
the measure. The mean radial velocity distribution is compared with the radial
{\deg}ow velocity. The thermal motion contributes an isotropic constant to mean
radial velocity