1. The problem statement, all variables and given/known data The surface charge density on an infinite charged plane is -2.6*10^-6 C/m^2. A proton is shot straight away from the plane at 2.2*10^6 m/s. How far does the proton travel before reaching its turning point? 2. Relevant equations Im very unsure of what equations to use, the only one I know is the equation for density charge. n=Q/A 3. The attempt at a solution Im trying to figure out how to incorporate kinematic equations with the electric field equations. I think I may need to use the force equation for the electric field somehow.