A Person’s Center of gravity (COG)

Standing in anatomical position, a person’s center of gravity (COG) sits just anterior to the second sacral vertebrae (S.2). How does the COG shift in the following scenarios?
a. holding a 20# dumbbell in their left hand ________________________________
b. holding an 80# barbell directly over their head ____________________________
c. holding a 50# box at waist level in front of them _____________________