The momentum of an electron is a sharp observable and the average of the momentum is 0. I assume this is because the velocity is direction dependent and positive, negative cancels. But for a particle in a 1D well, the absolute momentum is n(hbar)(pie)/L. Momentum is mv. The mass of the electron is a positive constant so v is a positive constant which depends on the excitation state of the electron. Hence having a momentum would mean having a velocity. But there is no trajectory of an electron. How do we measure the velocity of something without a trajectory? Velocity is defined as delx/delt. Could it happen that two successive measurements of the electron leads to delx/delt > c? Theoretically, I could tweak the above momentum formula and make L around 10^-12m for v=c although as always in QM the HP might intervene somehow. I suppose you could also define momentum as srt(2Em) or something else that does not depend on velocity. But I am curious about the idea of the velocity of an electron and whether it is possible to have one at all? And what would it mean for it to be a velocity?