5. The block diagram of a feedback control system is shown in Fig. 2. (a. 20 pts) Determine the disturbance model: Y(s)/D(s) and closed-loop transfer function model: Y(s)/Ysp(s). (b. 10pts ) If Ysp(s)=s1 and D(s)=s1, then determine if there exists a Kc to ensure the closed-loop stability. If yes, find the range of such Kc and the value of y(t=); If no, show the reason. Figure 2: Control Block Diagram for Question 5