1. The problem statement, all variables and given/known data Calculate the wavelength, in picometers, associated with an electron traveling 60.0% of the speed of light. 2. Relevant equations Wavelength = h / (mv) 3. The attempt at a solution I know the h value. The v value I believe it is 60.0% of 3.00 x 10^8 But what is the m value? If the m value isn't given, then the equation can't be solved, can it? Is there a specific number for the m value? From the examples I have seem, the m for electrons are always different. Please help. Thanks in advance.