The equation of motion for a damped vibration is given by 6x'' + 9x' + 27x = 0. The damping factor will be
- A. 0.25
- B. 0.5
- C. 0.35
- D. 0.75
Answer: C. 0.35
Explanation: m=6, c=9, k=27. Cc = 2*$\sqrt{mk}$ = 2*$\sqrt{6*27}$ = 2*$\sqrt{162}$ = 2*12.7 = 25.4. Zeta = c/Cc = 9/25.4 = 0.35.