1. The problem statement, all variables and given/known data Derive an expression for the total energy required to asemble a sphere of charge corresponding to a nucleus of atomic number Z and radius R. Assume the nucleus is a sphere of uniform volume charge density [tex]\rho[/tex] 2. Relevant equations [tex]\rho[/tex] = mass / volume = 3Am / 4*pi*R3 3. The attempt at a solution I know the solution is U = 3k * (Ze)2 / 5R, so I need to work on deriving this. I also know that when an alpha particle collides with the nucleus, the initial kinetic energy is equal to the electrical potential energy of the system and is given by .5mv2 = kq1q2/r = k(2e)(Ze)/d where d = 4kZe2 / mv2 Not sure how this helps though, but it seems to be in a relevant section in the textbook. There is also info on the binding energy, but it doesn't seem applicable in this case. Any tips on how to approach the problem, please?