Question

I know answer for 1 but two is what I need help with.

1) Determine expressions for the electric potential produced by a solid uniformly charged insulating
sphere having radius R and charge Q. Determine these expressions at a point, P, which is a distance r
from the center of the sphere. Include an expression for the region where r > R (outside the sphere)
and an expression for the region where r < R (inside the sphere). Hint: Apply the technique of field
integration.
2) Assume the sphere of problem (1) is configured with a narrow tunnel that extends through the center
of the sphere, from one end do the other. Also, assume the results from problem (1) are still valid. If a
particle having charge (q) and mass (m) is released at the center of the tunnel with a very small initial
speed, determine an expression for the speed of the particle when it reaches the surface of the sphere
(ie. when it leaves the tunnel).