1. The problem statement, all variables and given/known data Two 2.0cm diameter disks face each other, 1.0mm apart. They are charged to -10nC and 10nC. -What is the field strength between the disks? -A proton is shot from the negative disk toward the positive disk. What launch speed must the proton have to just barely reach the positive disk? 2. Relevant equations Q = (10*10^-9) ε0=(8.85*10^-12) radius = .1 m A = area of circle = πr^2 E = E(+) + E(-) = Q/ε0A vf^2 = vi^2 +2Ax 3. The attempt at a solution (10*10^-9)/(8.85^10^-12)(π)(.1^2) = 35.5 but the book gives it as (3.6 * 10^6) N/C b: vf^2 = vi^2 + 2AX vi= sqrt( vf^2+2(3.6*10^6)(.001)) = 84.85 book has it as 8.5 * 10^5 I think i am supposed to convert the distances meters or I need to do some type of conversion to get from the original answer to N/C units. I get the right answer but the precision is off. What could i be missing? Thanks!