An alpha particle with kinetic energy 17.0 MeV makes a head-on collision with a lead nucleus at rest. What is the distance of closest approach of the...

An alpha particle with kinetic energy 17.0 MeV makes a head-on collision with a lead nucleus at rest. What is the distance of closest approach of the two particles? (Assume that the lead nucleus remains stationary and that it may be treated as a point charge. The atomic number of lead is 82. The alpha particle is a helium nucleus, with atomic number 2.)