If $a$, $b$, $c$ are the $p^{th}$, $q^{th}$, and $r^{th}$ terms of a G.P., then what is the angle between the vectors $\overrightarrow{u} = (\log a)\hat{i} + (\log b)\hat{j} + (\log c)\hat{k}$ and $\overrightarrow{v} = (q-r)\hat{i} + (r-p)\hat{j} + (p-q)\hat{k}$?