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GATE 2025 ME – Question 35

Vibrations · Free vibration of single degree of freedom systems, damping · 1 mark · Numerical answer

A block of mass 1 kg connected to a spring of stiffness 10 N m$^{-1}$ is operating in a viscous medium such that the damping ratio (or damping factor) is equal to the ratio of the damped frequency to the natural frequency. The magnitude of the damping ratio for this system is ________ (rounded off to 2 decimal places).

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Correct answer: 0.70 to 0.72

Explanation

The damped frequency is $\omega_d = \omega_n\sqrt{1 - \zeta^2}$, so the ratio $\frac{\omega_d}{\omega_n} = \sqrt{1 - \zeta^2}$. Setting $\zeta = \sqrt{1 - \zeta^2}$ gives $\zeta^2 = \frac{1}{2}$, so $\zeta = 0.71$.