For the system shown, use the energy method to find the natural frequency $($Hz$)$

Disk Mass M$=10$ Lb$,$ Disk Radius r $=6$ in$,$ Spring Stiffness K $=20$ Lb$/$in Mass m $=5$ Lb K P$.$S$.$ Disk Mass moment of inertia J$=1/2$ M r$2$ For the system shown, use the energy method to find the natural frequency $(Hz)$

Disk Mass M$=10$ Lb

Disk Radius $r=6$ in

Spring Stiffness K $=20L\frac{b}{?}$ in

Mass $m=5Lb$