Posted by so CONFUSED! on .
I'm having trouble relating Work, with Electric Field, with Kinematics. The question is asking:
How fast and what direction is the particle moving, given:
Disk: radius = 0.1m, surface charge density = 3.7mC/m2
Particle: 4.5 mC, mass = 75 mg accelerates from a point perpednicular from the center of the disk, with a final speed = 1.0 m/s
Work done on particle is 3 mJ
I think my main obstacle is finding the change in distance of the particle when I try to relate these variables.
Any help is appreciated, thank you.

Physics 
drwls,
It is not clear what they are asking for. Does the particle start with zero velocity? You ask for a final velocity and yet they tell you what the final speed is. The velocity direction will remain along the axis, if it started out that way.
The E field will be uniform as the charge moves the first 0.03 m away from the surface , and then vary with 1/x^2 as the distance from the surface exceeds 0.3 m.
The negative work done on the particle means there is an attractive force to the plate, so it is always slowing down.