1. The problem statement, all variables and given/known data An electron is rotating around a proton (at rest) in a perfect circular orbit. If the radius of the orbit is r=10^-10 m, how long is the rotation period [hint: the radial acceleration is entirely due to the electric force] k=9*10^9 q=1.6*10^-19 2. Relevant equations 1. F=(k*q^2)/r^2 2. arad=(angular velocity)^2*r 3. The attempt at a solution I found the force by equaiton 1., and I got 2.3*10^-8 N ((9*10^9)(1.6*10^-19)^2))/((10^-10)^2) I tried equation 2. to get (angular velocity)=sqrt(F/r) and got 15.2 rad/s This means that it is 2.4 rev/s (by dividing by 2pi) and 0.41 seconds per orbital period. That is like the world's slowest electron. Where did I go wrong?