Finding where I made an error in a Coulomb force calculation

[baller2353]

Homework Statement

Constants Given
Colombs constant = 9 x 10^9
Charge of Proton = 1.6 x10^-19
Proton rest mass=1.673 x 10-27
Charge of electron = -1.6 x 10^-19
Electron Rest Mass = 9.11 x 10^-31 kg

Homework Equations

On the attachement

The Attempt at a Solution

On the attachement

Can anyone tell me what i did wrong in my attempt to solve the question.

 

[Delphi51]

That red mark sure isn't clear! It does indicate that Vi*t = 0 but not that half the solution has been left out.
You have for the vertical part of the motion
d = Vi*t + ½*a*t²
The Vi vertically is zero, so forget the Vi*t. The next line should read:
.01 = ½*a*(5x10-⁹)²
That should be solved for the acceleration.
Then, use that value to calculate the vertical force, electric field and finally the voltage across the parallel plates that causes the electric field that causes the force on the electron.