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Centroid of Area Example

Easy DifficultyFE Statics

Find the centroid (center of area) of an L-shaped region made of two rectangles.

Concept

The centroid of a composite area is the weighted average of the centroids of its parts: and , where is the area of part and is the centroid of that part.

Notation: = coordinates of centroid of composite, = area of part i.

Problem

An L-shaped area consists of two rectangles: Rectangle 1 is 6 m wide by 2 m tall with its bottom-left corner at the origin. Rectangle 2 is 4 m wide by 2 m tall, placed so its left edge is at x = 4 m and its bottom edge at y = 2 m (so it sits on top of and to the right of part of rectangle 1). All dimensions in meters.

Find:

Coordinates of the centroid of the composite area.

Given

  • Rectangle 1: 6 m × 2 m, bottom-left at (0, 0)
  • Rectangle 2: 4 m × 2 m, bottom-left at (4, 2)

Area and centroid of each part

Composite centroid

Final Answer

Centroid: , .

Key Formulas

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