1. The problem statement, all variables and given/known data Two identical point charges with a mass <i>m</i> and equal charge <i>q</i> repel each other at the end of a lightweight rope of length L=12.5cm. The angle θ is 17.5 degrees. a)What is the mass <i>m</i>? b)What is the charge <i>q</i>? 2. Relevant equations Fx= Fe-Tcosθ=0 Fy=mg-Tsinθ=0 Fe=kq1q2/r^2 3. The attempt at a solution I have a free body diagram drawn up(don't know how to post them sorry) of the left ball, with the Fg acting downwards, the Ft acting towards the connecting point with the ceiling and the Fe pointing horizontally away from the opposite sphere. The problem I'm having is I don't know how to find the mass since it seems no matter how I try to go about solving this equation I always have two unknowns. I cannot tell if I'm just missing something simple by looking too hard at it, but I can't seem to figure out where to start. Any suggestions?