14. A solid sphere of radius R carries a total charge Q, uniformly distributed in the volume of the sphere. (a) What is the charge density? (b) Employ Gauss's dielectric flux theorem to calcuiate the electric field inside the sphere, at distance r R from the center of the sphere? (Showing a derivation is not necessary.) (d) Using your expressions for the clectric field, find the electric potential V (r), outside the sphere and inside the sphere. 15. A ball of known charge q and unknown mass m, initially at rest, falls freely from a height h in a uniform electrie field E that is directed vertically downward. The ball hits the ground at a speed v 2vgh. Find m in terms of E, q and g.