What Is the Method Used in Finding the Centroid?


Quick Answer

The method of determining the centroid depends on the type of area in question. Finding the centroid is conducted through either geometric illustration, the concept of moment, or integral calculus.

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Full Answer

The centroid of a two-dimensional region is defined as the point of perfect balance, with the assumption that the region has uniform density and gravitational field. In geometry, the centroid is the arithmetic average position of all points on the given region. For any flat surface, the centroid can be considered its center of gravity.

Finding the centroid of regular polygons is easy to do. For triangles, the centroid is the intersecting point of its three medians. For rectangles, this point can be found by the intersection of the line segments connecting opposite midpoints of the four sides.

For more complex polygons, the concept of moment is used to find the centroid. The moment of any object is the measurement of its inclination to rotate about a given point of reference. It can be calculated as the mass (or area) of the object multiplied by its distance from the point. The polygon is cut into triangles and quadrilaterals so that the centroids of all cut shapes may be determined. To get the coordinates of the centroid, the summation of the moments of each cut shape should be equated to the area of the entire polygon multiplied by the distance of the centroid from the point of reference.

The same approach is implemented to determine the centroid of curved regions, but this time using integral calculus. The area is defined by limits, more particularly by bounding curves with given algebraic equations. The equations form the basis for calculating the moment of each incremental element of the curved area, and divide the total moment with the total area.

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