f=(k*q1*q2)/(r^2)

r approximately = r0 * v0*t * 0.5*a*t^2

f=ma

a=f/m

So how do I calculate the force if it depends on the distance (radius) and the distance depends on the force?

More stuff you already know:

integrate(acceleration with respect to time)=velocity

integrate(velocity with respect to time)=distance (radius)

Looks like this is the same problem one would have trying to figure out when a rock drop from far above the Sun would hit it.

Let me know if you have any suggestions on how to find the function I'm looking for.

Thanks in advance,

Daniel