9.4 : Centroid of a Body: Problem Solving

The centroid of a body is a crucial concept in engineering and physics. Finding the centroid of a body can help determine its stability, its balance point, and even its design. In this context, consider a thin wire bent in the form of a quarter circular arc. Polar coordinates are used to calculate the centroid. The wire is first divided into small differential elements of a length equal to the radius multiplied by the differential angle.

The x-coordinates and y-coordinates of each element's centroid can then be expressed in terms of the radius and the angle made by the element with respect to the x-axis. The centroid of the arc is then obtained by computing a weighted average of all these elements, where each element's weight is proportional to its length.

Since the wire is a quarter circle, the differential element can be integrated from the limits of zero to π/2. The result gives the centroid coordinates for the quarter circle wire segment. In this case, the x-coordinates and y-coordinates of the centroid are numerically equal due to the circular symmetry of the problem.

This method can also be applied to determine the centroid of curved arch trusses. The calculated centroid, in turn, can be used to determine the maximum load the arch can carry without collapsing or the forces acting on specific points of the arch. Knowing the centroid of a body offers numerous advantages in engineering and is crucial to the design and stability of structures.