1. The problem statement, all variables and given/known data 2. Relevant equations r=mv/qb mv=sqrt(2*KE*m(alpha)) m(alpha)=6.64e-27 kg 3. The attempt at a solution i was just wondering how to get the answer (7.6e-4 m). i get path curving down, and do r=sqrt(2*1e3eV*6.64e-27kg*1.6e-19J/eV)/(q*B) =15.18e-4m so to get the right answer i would have to divide this by 2..why is this?? i used the right equation but am I doing something wrong?