218.  The unit step response of a second order linear system with zero initial states is given by c (t) = 1 + 1.25 exp (-6t) sin (8t - tan-1 1.333); t > 0 The damping rafio and the undamped natural frequency of oscillation of the system are respectively
A. 0.6 and 10 rad/s
B. 0.6 and 12.5 rad/s
C. 0.8 and 10 rad/s
D. 0.8 and 12.5 rad/s

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219.  Which one of the following statements regarding the state transmition matrix is correct?
A. 0(0) = 0
B. 0-1 (t) = ()
C. 4)(t1 + t2) = 4?(t1) + 0(t2)
D. 002 - ti) 4)(t1 - to) = 4)(t2 - to)

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220.  A control system whose step response is 0.5 (1 + e-2t) is cascaded to another control block whose impulse response is e4. The transfer function of the cascaded combination is
A.150
B. 30?
C.450
D.600

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221.  The characteristic equation of a closed loop control system is given by 52 + 9s + 16 = 0. The resonant frequency in radians/sec of the system is
A.2
B. 2?IF
C.4
D. 413-

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222.  For a unit step input, a system with forward path transfer, function G(s)20= -7 and feedback path transfer function H(s) = (s + 5) has a steady state output of
A.20
B.5
C.0.2
D. zero

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223.  The transfer function of a multi-input multi-output system with the state-space representation of X = AX + BU Y = CX + DU where X represent at state, Y the output and U the input vector, will be given by
A. C(s1 - A)'
B. C(s1 -
C. (sI - A)-1 B + D
D. C(s1 - A)-1 B

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224.  The unit impulse response of a unit feedback control system is given by c(t) = -e-t + 2e-t (t > 0) The open-loop transfer function is equal to
A. s + 1(2s + 1)
B. (s + 2)2
C. (s + 1)2
D.s + 1(s +0)2

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