  We solve numerically the equations of motion for the collapse of a shell of
baryonic matter, made of galaxies and substructure of $ 10^{6} M_{\odot} \div
10^{9} M_{\odot}$, taking into account the dynamical friction and the
parameters on which it depends: the peaks' height $\nu_{c}$, the number of
peaks inside a protocluster $N_{tot}$ multiplied by the correlation function
$\xi (r)$ evaluated at r=0, the filtering radius $R_{f}$ and the core radius of
the cluster of galaxies, r_0. We show how the collapse time of a shell of
baryonic matter depends on those parameters.
