The unit step response of a second order system is = 1-e-5t-5te-5t. Co...
Answer: d
Explanation: C(s) = 1/s-1/s+5-5/(s+5)^2
C(s) = 25/s(s2+10s+25)
R(s) = 1/s
G(s) = 25/(s2+10s+25 )
w= √25
w = 5 rad/sec
G = 1.
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The unit step response of a second order system is = 1-e-5t-5te-5t. Co...
Explanation:
To determine the correctness of the given statements, let's analyze each statement separately.
Statement 1: The underdamped natural frequency is 5 rad/s.
The unit step response of a second-order system is given by:
y(t) = 1 - e^(-ζωn*t) * (cos(ωd*t) + (ζ/√(1-ζ^2))*sin(ωd*t))
where ζ is the damping ratio and ωn is the undamped natural frequency.
Comparing the given unit step response with the general form, we can see that e^(-5t) term corresponds to e^(-ζωn*t) term in the general form. Therefore, we can conclude that ζωn = 5.
Since the system is underdamped, the damping ratio ζ should be less than 1. From the given information, we cannot determine the exact value of ζ. So, statement 1 is partially correct.
Statement 2: The damping ratio is 1.
From the previous analysis, we found that ζωn = 5. If we assume ζ = 1, then ωn = 5/ζ = 5. Therefore, the damping ratio is not equal to 1. So, statement 2 is incorrect.
Statement 3: The impulse response is 25te^(-5t).
The impulse response of a second-order system is given by:
h(t) = (ωn^2/√(1-ζ^2))*e^(-ζωn*t)*sin(ωd*t)
Comparing the given impulse response with the general form, we can see that the given impulse response does not match the general form. Therefore, the statement 3 is incorrect.
Conclusion:
From the analysis above, we can conclude that only statement 1 is correct. Therefore, the correct answer is option 'D' - 1, 2, and 3.