The mass of an object can be imagined as many points spread throughout the entire surface area or volume. The gravitational pull a body experiences by the force of gravity, makes a body accelerate downwards. The object’s weight therefore is distributed over the entire volume of the body. To simplify calculations such as computing moments and forces, the body’s weight can also be imagined as acting on a single individual point – the center of its mass. It is as if the entire mass is concentrated at this infinitely small point. Moreover, at the point the body is at equilibrium.
The mathematical operation to obtain the centroid is expressed as
X(center) = (X1+X2+X3+ … Xn)/N = ΣXi/N
where ΣXi/N is the sum of all distanced from the applied force to the axis and N the total number of applied forces.