There are
Z
protons in the nucleus of an atom, where
Z
is the atomic number of the element. An
\alpha
particle carries a charge of
+2e
. In a scattering experiment, an
\alpha
particle, heading directly toward a nucleus, will come to a halt when all the particle's kinetic energy is converted to electric potential energy. In such a situation, how close will an
\alpha
particle with a kinetic energy of
4.40\times 10^(-13)J
come to a nucleus with atomic number
Z=89
?