1. What is the magnitude of the electric field at a distance of 3.10 ×10-10 m from a neptunium nucleus?

The answer I got is 1.39×1012 N/C.

2. What is the magnitude of the force on an electron at that distance?

2.23×10-7 N F=qE.

3. Treating the electron classically, that is, as a point object that can move around the nucleus at reasonably slow speeds, what is the period of the electron's motion?

The answer is

**2.23×10-16 s**but I am unable to calculate this.

I tried taking the Force from part 2 and using F=ma. Then using a to find velocity. Then used that to find T.

4. Again treating the electron classically, how fast it it moving?

The answer is

**8.72×106 m/s**, again no idea what I did wrong but I can't find this answer.

Many thanks.