Consider the system shown in the figure. A rope goes over a pulley. A mass, 𝒎, is hanging from the rope. A spring of stiffness, k, is attached at one end of the rope. Assume rope is inextensible, massless and there is no slip between pulley and rope.

The pulley radius is 𝒓 and its mass moment of inertia is 𝑱. Assume that the mass is vibrating harmonically about its static equilibrium position. The natural frequency of the system is