Two alpha particles (helium nuclei), each consisting of two protons and two neutrons, have an electrical potential energy of 6.11 × 10^?19 J. What is the distance between these particles at this time? The Coulomb constant is 8.98755 × 10^9 N · m^2/C^2, the elemental charge is 1.6021 × 10^?19 C, and the acceleration due to gravity is 9.8 m/s^2.