1. The problem statement, all variables and given/known data see attachment 2. Relevant equations r=RoA1/3 Ro=1.2*10-15 3. The attempt at a solution 35 kiloelectron volts = 5.60761762 × 10-15 joules I could calculate the velocity if I knew mass but that wouldn't help with the radius? I think that I need to find A from the energy but how do I do that?