Radium decomposes radioactively to form radon (atomic number 86, which is also the number of protons in the nucleus) by emitting an alpha-particle from its nucleus. The mass of an alpha-particle is 6.6404 x 10^-24 grams. What is the force of repulsion between the radon nucleus and the alpha-particle, when the distance between them is 5 x 10^-11 cm? What is the acceleration of the alpha-particle at this distance? I am not sure what equation I need to use to solve this equation. Any help would be appreciated!