1. The problem statement, all variables and given/known data If the density of the half-ball x ^2 + y ^2 + z ^2 ≤ 4 ; z ≥ 0 is given by δ(x, y, z) = ( x^ 2 + y^ 2 + z ^2)^(1/2) find its mass. 2. Relevant equations ∫∫F⋅ds ∫∫FoΦ(u,v)||Tu,Tv||dudv ∫∫FoΦ(u,v)⋅(Tu,Tv)dudv 3. The attempt at a solution For the last problem I was asked to find the density of the shell and used the equation ∫∫FoΦ(u,v)||Tu,Tv||dudv, but now I don't know if I use the same thing or not. I know how to parametrize it and know that it will be a ball of radius 2 but don't know if I use the same equation or not.