1. The problem statement, all variables and given/known data I'm having problem with a couple parts of this problem. I know how to work it (I think), but I'm consistently off by a couple orders of magnitude off the answer provided by the professor. I've already found that the isotope 90SR+ needs to be given a speed of 25.72*10^4 m/s. This much I know is correct. From there I am asked to find the voltage difference required to accelerate the isotope to this speed. 2. Relevant equations U=qV U=.5mv^2 q (elementary charge): 1.602*10^-19 C m (mass of isotope): 1.495*10^-25 Kg 3. The attempt at a solution Set the two equations equal to one another. Find the kinetic energy of the isotope traveling at the needed speed. Divide this value by q (charge of a +1 ion). I get the answer 30866.73 V. Professor gets roughly 308 volts. Granted, his answer makes more sense than mine, but I cannot for the life of me find the fault in my work. Note: I calculated the mass of the isotope, but since it yielded the correct answer in a previous question, I assume it is correct. Someone tell me how the hell I'm off by two orders of magnitude?