Question: A rotor system such as the one shown in Figure consists of a disk with the mass moment of inertia J = 0.1 kg-m2 , a damper with viscous
damping coefficient c = 6 N-m-s/rad, and a rotary spring of unknown stiffness k. When applying a step input m = 20 N-m to the disk, it is determined experimentally that the steady-state response is io(3) = 4°. Evaluate the spring constant using the transfer function approach and plot the system response for a rotor initial velocity ~(0) = 40 rad/s and the unit step input of MATLAB®.