Question

b) In your own words describe first moment of area for any shape and its importance. With reference to the shape below about the axis s – s, describe the position of the centroid.

Answer 1

So, we have a shape. Imagine a hollow pyramid with x-axis passing through its vertex. The first moment of area shows how much of the shape's area is distributed around the given axis. For example, the first moment of area is the same for all axes passing through the center of a ball, cube, but it will be different for pyramids and tetrahedron.

The centroid is the center of mass of an object of uniform density. You may attach a figure (by attaching a link for the image, for example) to get more help.