Centre of mass and centroid of a body

This model is designed to show that the location of the centre of mass of a body can be different from that of the centroid of the body.

A 300mm tall pendulum model is made of wood. The model consists of a supporting base, a mast fixed at the base and a pendulum pinned at the other end of the mast as shown in Fig. 2-6. A metal piece is inserted into the right arm of the pendulum. The centre of mass of the pendulum must lie on a vertical line passing through the pinned point. The centroid of the pendulum lies on the intersection of the vertical and horizontal members. Due to the different densities of wood and metal, the centroid of the pendulum does not coincide with the centre of mass of the body.