For a rigid slab in centroidal rotation, show that the system of the effective forces cons...

For a rigid slab in centroidal rotation, show that the system of the effective forces consists of vectors attached to the various particles Pi of the slab, where ω and α are the angular velocity and angular acceleration of the slab, and where  denotes the position of the particle Pi relative to the mass center G of the slab. Further show, by computing their sum and the sum of their moments about G, that the effective forces reduce to a couple