Problem 4. For the standard form second-order system, answer following questions: (1) IF a pole is moved with a constant real part as shown in Figure 4(1), plot the unit-step responses as poles move. What will the responses have in common? (2) If a pole is moved with a constant imaginary part as shown in Figure 4(2), what will the unit-step responses have in common? And plot the response curves as poles move. (3) IF a pole is moved with a radial line extending from the origin as shown in Figure 4(3), what will be the response have in common? Plot the response curves as poles move. jo s-plane jo ja 21 s-plane s-plane Pole motion * 2 Pole motion ** 21 (1) (2) (3) Figure 4 Pole motion 2/2 :::