1. The problem statement, all variables and given/known data F = k(Q2*Q1)/(r^2) 2. Relevant equations 3. The attempt at a solution I asked my teacher and he said that this is an inverse square law. Didn't say anything else. He also mentioned k is constant. I assume i can plug in random values and see if there is a pattern... k=1 for all Set 1, q1 = 2, q2 = 4, r = 5 F1 = 8/25 Set 2, q1 = 1 q2 = 5, r = 4 F2 = 5/16 I plugged in random values but i don't really get it. What is inverse of what? I see that the r is squared and its below the kq1q2. I'm stuck. Any advice is appreciated.