  If a galaxy cluster is effectively in dynamical equilibrium then all galaxy
populations within the cluster must have distributions in velocity and position
that individually reflect the same underlying mass distribution, although the
derived virial masses can be quite different. Specifically, within the CNOC
cluster sample the virial radius of the red galaxy population is, on the
average, a factor of $2.05 \pm 0.34$ smaller than that of the blue population.
The red galaxies also have a smaller RMS velocity dispersion, a factor of $1.31
\pm 0.13$ within our sample. Consequently, the virial mass calculated from the
blue galaxies is $3.5 \pm 1.3$ times larger than from the red galaxies.
However, applying the Jeans equation of stellar-hydrodynamical equilibrium to
the red and blue subsamples separately give statistically identical cluster
mass profiles. This is strong evidence that these clusters are effectively
equilibrium systems, and therefore empirically demonstrates that the masses in
the virialized region are reliably estimated using dynamical techniques.
