1. The problem statement, all variables and given/known data This is from an old exam I'm studying from. It goes: "A particle of mass m is traveling in one dimension under the influence of a potential V = -Fx where F is a known constant. Find the energy spectrum and wavefunctions. Hint: You may want to work in momentum space, but do not have to." 2. Relevant equations Schrodinger eqn, other fundamental quantum relations 3. The attempt at a solution I solved for the momentum space wave function and got an exponential solution ~ exp[(i/hF)(p^3-E*p)], I think, or something much like that. But how can I find an energy spectrum when I don't seem to have any boundary conditions? It does not say anything about, say, an infinite potential for x < 0 or anything. I also tried using d<p>/dt= <-dV/dx> but that didn't seem to help. It seems like the energy could be anything. Could that be all I need to say? And what about the wave functions? It just seems like a weird problem. I'm wondering if there could have been a typo or something obvious I'm missing. I can post more of my work if it will help.