1. The problem statement, all variables and given/known data A proton with speed v = 3.42 x 106 m/s orbits just outside a charged sphere of radius r = 0.862 cm. What is the charge in coulombs on the sphere? 2. Relevant equations (k*q1*q2)/r^2 F = mv^2/r Gauss Law for sphere, possibly? I'm not sure if I need this. 3. The attempt at a solution setting the equations equal to eachother and then solving for q2 kq1q2/r2 = mv^2/r rearranged... q2= mv^2r/kq1 m = mass of proton = 1.672e-27 q1 = charge of proton = 1.602e-19 v = 3.42e6 r = .00862 m Values subbed in... q2 = [(1.672e-27)*(3.42e6^2)*(.00862)] / [(9e9)*(1.602e-19)] I get 1.1696e-7 which is incorrect.