1) A massless rod connects a mass M on one end to a mass 3M on the other. The mass M is at (a, (1,0) and the mass 3M is at (a, a,0). a) Find the centre of mass. b) Find the inertia tensor in terms of the given coordinates. c) Find the principal axes for this system. Note: your derivation need not be based on nding the eigenvectors of b). You can use symmetry arguments to nd these instead. (:1) Find the principal moments of inertia