Let $W$ be the top half of the unit sphere centered at the origin. Without calculating, determine whether each integral below is positive, negative, or zero.

? Positive Negative Zero  1. $\displaystyle \iiint\limits_W (z^2-z) \, dV$

? Positive Negative Zero  2. $\displaystyle \iiint\limits_W -xz \, dV$