1. The problem statement, all variables and given/known data http://img340.imageshack.us/img340/3249/question.jpg [Broken] 2. Relevant equations P=h/lambda E=p^2/2m 3. The attempt at a solution Well, I calculated P using a wavelength of .1 femtometer. Then I plugged it into the energy equation. However, I got 1.5e14 eV, while the answer sheet says it's supposed to be 12 GeV. Have I done something wrong wrong? On the answer sheet my professor calculated P, and I got the same answer he got, but after that he just says therefore E=12GeV, not showing how he came to that conclusion. Thanks for any help!