Railways Technical Ability Vibration Analysis Question Bank Vibration Analysis

  • question_answer A spring-mass suspension has a natural frequency of 40 rad/s. What is the damping ratio required if it is desired to reduce this frequency to 20 rad/s by adding a damper to it?

    A) \[\frac{\sqrt{3}}{2}\]                             

    B) \[\frac{1}{2}\]

    C) \[\frac{1}{\sqrt{2}}\]                             

    D) \[\frac{1}{4}\]

    Correct Answer: A

    Solution :

    \[{{\omega }_{d}}={{\omega }_{n}}\sqrt{1-{{\zeta }^{2}}}\] \[20=40\sqrt{1-{{\zeta }^{2}}}\] \[1-{{\zeta }^{2}}=\frac{1}{4}\] \[{{\zeta }^{2}}=\frac{3}{4},\] \[\zeta =\frac{\sqrt{3}}{2}\]

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