1. The problem statement, all variables and given/known data 2. Relevant equations If i can make that out its Ep=kq1q2/r where k is coloumbs constant 3. The attempt at a solution Im a little confused how do i know the radius of the alpha particles? I was thinking its conservation of energy, Ep+Ek=Eka then try to solve for a that way, but would Fnet be 0 on this alpha particle?