The mass m, Fig. 5-12, is free to move along a smooth horizontal rod under the action of the spring. When the mass is in its equilibrium position the spring is still stretched. Show that for small displacements from equilibrium the potential energy is closely approximated by V = k(8-10) 28 where lo is the unstretched length of the spring. wwwwww Fig. 5-12 m x + klo 883 M Fig. 5-13 B