1. The problem statement, all variables and given/known data A proton is accelerated from rest through a potential difference of 107 V. Calculate the final speed of this proton. 2. Relevant equations I'm not really sure which equations to use, but I figured I give all I tried... V=-Ed V=PE/q PE=-qEd and I think this applies...v(f)^2= v(i)^2 + 2ad 3. The attempt at a solution I really can't figure out what equation i should use. What I did was.. 1)used the equation V = Ed 2) becomes V= Kc(q/d^2)d 3) becomes V=Kc(q/d) 4)107= 8.99x10^9 (1.602x10^-19)/d 5)Solved for d and found it was 1.34598 x 10^-11 6) used the equation v(f)^2= v(i)^2 + 2ad 7) became v = sqrt (2a (1.34598x10^-11) ....but I don't know what "a" is so I can't solve. Any help would be greatly appreciated. I gave this a shot and really couldn't figure it out. Thanks, everyone.