Question: is centroid the same as center of gravity

Answer: No, In mathematics and physics, the centroid or geometric center of a plane figure is the arithmetic mean (``average'') position of all the points in the shape. The definition extends to any object in n-dimensional space: its centroid is the mean position of all the points in all of the coordinate directions. Informally, it is the point at which a cutout of the shape could be perfectly balanced on the tip of a pin.