  Matter accreting onto black holes may develop shocks due to the centrifugal
barrier. A part of inflowing matter in the post-shock flow is deflected along
the axis in the form of jets. Post-shock flow which behaves like a Compton
cloud has `hot' electrons emiting high energy photons. We study the effect of
these `hot' photons on the outflowing matter. Radiation from this region could
accelerate the outflowing matter but radiation pressure should also slow it
down. We show that the radiation drag restricts the flow from attaining a very
high velocity. We introduce the concept of an `equilibrium velocity' ($v_{eq}
\sim 0.5c$) which sets the upper limit of the terminal velocity achieved by a
cold plasma due to radiation deposition force in the absence of gravity. If the
injection energy is $E_{in}$, then we find that the terminal velocity
$v_\infty$ satisfies a relation $v_\infty^2 \lsim v_{eq}^2 + 2 E_{in}$.
