i.11.5 Triple integrals

Find the coordinates of the center of gravity of a homogeneous body \( V \), bounded by the surfaces \( S_{1}, S_{2}, S_{3} \), where \[ S_{1}: x^{2}+y^{2}+z^{2}=1, \quad S_{2}: x=0, \quad S_{3}: y=0 . \]