M.I. if this rectangle about xx and yy axis will be, 1= = 1 = 162226666.7 mm4 1 = = 1 = 306666.67 mm4  2 = G2 = = 106666666.7 mm4 Consider rectangle ABCD area ③ 3 = 461066666.7 mm4 3 = 106666666.7 mm4 = 1 + 2 + 3 = 1084.36 106 1 + 2 + 3 = 213.64 106 mm4

2 = G2= A2h22 h22 + (4002) 2 = 461066666.7 mm4 
As this figure is symmetrical about Y axis X = 100 mm Y = There , area ① = rectangle area ② = triangle area ③ = circle Y = 79.95 mm to find M.I. of shaded portion , let G is the centroid of shaded area which is at y = 79.95 mm from base. of shaded portion @ xx axis passing through its centroid G will be, xx) + xx) – xx axis) 1 + 23 = (G1 + A1h12) + G2 + A2h22)  G3 + A3h32) = + 60] + + – 84329013.21 mm4 of shaded portion about yy axis passing through its centroid G will be, yy) + yy axis) – yyaxis) 1 + 23 = = 80000000 + 16666666.67 – 3220623.34 93446043.33 mm4







Difference Between Center of Gravity and Centroid  
Center of Gravity  Centroid 
The point where the total weight of the body focuses upon  It is referred to the geometrical center of a body 
It is the point where the gravitational force (weight) acts on the body  It is referred to the center of gravity of uniform density objects 
It is denoted by g  It is denoted by c 
Center of Gravity in a uniform gravitational field is the average of all points, weighted by local density or specific weight  The centroid is a point in a plane area in such a way that the moment of area about any axis throughout that point is 0 
It is a physical behaviour of the object, a point where all the weight of an object is acting  It is a geometrical behaviour. It is the center of measure of the amount of geometry. 