eslion. A plutonium-239 nucleus, initially at rest, undergoes alpha decay to produce a uranium-235 nucleus. The uranium-235 nucleus has a mass of 3.90 x 10-25 kg, and moves away from the location of the decay with a speed of 2.62 x 105 m/s. Determine the minimum electric potential difference that is required to bring the alpha particle to rest. Marks will be awarded based on the physics principles you provide, the formulas you state, the substitutions you show, and your final