  The cross section for coincidence, quasielastic proton knock-out by electrons
from a polarized K39 nucleus is computed in DWIA using an optical potential in
describing the wave function of the ejected nucleon. The dependence of the FSI
on the initial polarization angles of the nucleus is analyzed and explained in
a new, semi-classical picture of the reaction in which the nuclear transparency
decreases as a function of the amount of nuclear matter that the proton has to
cross, thus providing a method for obtaining detailed information on its mean
free path in finite nuclei. We propose a procedure to find the best initial
kinematical conditions for minimizing the FSI which will be useful as a guide
for future experiments with polarized nuclei.
