  Height-time plots of the leading edge of coronal mass ejections (CME) have
often been used to study CME kinematics. We propose a new method to analyze the
CME kinematics in more detail by determining the radial mass transport process
throughout the entire CME. Thus our method is able to estimate not only the
speed of the CME front but also the radial flow speed inside the CME. We have
applied the method to a slow CME with an average leading edge speed about 480
km s$^{-1}$. In the Lagrangian frame, the speed of the individual CME mass
elements stay almost constant within 2 and 15 R$_S$, the range over which we
analyzed the CME. Hence we have no evidence of net radial forces acting on
parts of the CME in this range nor of a pile-up of mass ahead of the CME. We
find evidence that the leading edge trajectory obtained by tie-pointing may
gradually lag behind the Lagrangian front-side trajectories derived from our
analysis. Our results also allow a much more precise estimate of the CME
energy. Compared with conventional estimates using the CME total mass and
leading-edge motion, we find that the latter may overestimate the kinetic
energy and the gravitational potential energy.
