an alpha particle with kinetic energy 11.0 MeV makes a head on collision with a gold nucleus at rest. what is the distance of closest approach of the...

an alpha particle with kinetic energy 11.0 MeV makes a head on collision with a gold nucleus at rest. what is the distance of closest approach of the two particles? (Assume that the gold nucleus remains stationary and that it may be treated as a point charge. The atomic number of gold is 79, and an alpha particle is a helium nucleus consisting of two protons and two neutrons.)