1. The problem statement, all variables and given/known data The voltage between two plates is 15kV. If an electron's speed is zero as it leaves the anode, what is its speed just before it hits the cathode? 2. Relevant equations U=q*V 3. The attempt at a solution I guess my question is can I use the equation Ui + Ki = Uf + Kf and since there is no initial kinetic anergy and no final potential energy can I substitute Kf of the electron in for the U in the equation U=q*V? Would q be the charge of the electron?