  It has been shown that the thermal photon and the lepton pair spectra can be
used to estimate the radial velocity of different phases of the matter formed
in nuclear collisions at ultra-relativistic energies. We observe a
non-monotonic variation of the flow velocity with invariant mass of the lepton
pair which is indicative of two different sources of thermal dilepton sources
at early and late stage of the dynamically evolving system. We also show that
the study of radial velocity through electromagnetic probes may shed light on
the nature of the phase transition from hadrons to QGP.
