1. The problem statement, all variables and given/known data A molecule is 3 nanometers wide and weighs 5 x 10^-15kg. It is fired through a slit that is 5 nanometers wide. Approximately how slow does the molecule have to go so that it diffracts? 2. Relevant equations I'm thinking that I could use De Borglie's wavelength equation: λ=h/m=h/mv and then solve for v but since I don't know that lambda is I don't see how I can use it. Does anyone have a clue on how to solve this?