1. The problem statement, all variables and given/known data A positively charged particle initially at rest on the ground accelerates upward to 200m/s in 2.60s. The particle has a charge-to-mass ratio of 0.100 C/kg and the electric field in this region is constant and uniform. What are the magnitude and direction of the electric field? 2. Relevant equations F=ma a=delta v/ delta t Electric Fields E=F/q Coulomb's Law F=kq/r^2 Not sure I need this one. 3. The attempt at a solution E=F/q=ma/q=(m/q)a E=(10 kg/C)(200/2.6 m/s^2) = 769.23 N/C = 7.7*10^2 N/C Direction upward. Question seems pretty straightforward but it's telling me this answer is incorrect. If I have to incorporate Coulomb's law, I'm not sure how.