A ring of charge is situated in the x‐y plane centered about the origin. The ring has a
uniformly distributed charge Q = ‐10 nC and a radius R = 2.0 cm.
a. Find the electric potential at a distance z = 5.0 cm above the origin on the z=axis.
b. Find the electric field at a distance z = 5.0 cm above the origin on the z=axis.
c. Find the speed of a proton as it passes through the origin assuming that it is
released from rest at z=5.0 cm.
The Attempt at a Solution
After solving to get this
=(8.998x10^9)(10x10^-6)(0.05m) / (0.05^2+0.02^2)^3/2
Now I feel like this is really easy to get a, but I can't seem to get it. And c is just blew my mind.