Question

In the first moment of area equation Q = Ey;A;, the term y; is the distance between the and the centroid of shape i.

Answer 1

Ans. In the first moment area equation Q= $Q= \sum yiAi$ . The term Yi is the distance between the neutral axis (NA ) and the centroid of shape i.

It is also called as statical moment. It is always taken at a distance from centroidal axis to neutral axis of object.

First moment of area is used to measure area distribution of shape in relationship with the axis we consider for evaluation.

It is the sum of area multiplied by distance to an axis. It is useful for calculations of area distribution, shear flow and also to know the shape of symmetry.

Generally we use first moment of area to determine centroid of an object.