1. The problem statement, all variables and given/known data an electron is held up against the force of gravity by the attraction of a fixed proton some distance above it. How far above the electron is the proton? 2. Relevant equations F= ((K)(Q1)(Q2))/R^2 Qe = 1.6x10^-19 3. The attempt at a solution Using the formula for Coulombs Law I used the K constant of 9x10^9 and Qe for Q1 and Q2. This is all divided by R^2 (I'm solving for R). The problem is I don't know if there is a gravitational constant for Force or what I'm missing. What's the next step?