A machine rests on spring mounts, which compress by 8 mm under its weight. Treat it as an undamped single-degree-of-freedom system and use g = 9.81 m/s². Find the natural frequency fn of vertical vibration in Hz.
Mechanical vibrations worksheet with answers
A machine rests on spring mounts, which compress by 10 mm under its weight. Treat it as an undamped single-degree-of-freedom system and use g = 9.81 m/s². Find the natural frequency fn of vertical vibration in Hz.
An 80 kg mass on a spring with a stiffness of 10 kN/m has a viscous damper giving a damping ratio of 0.5. Find the damped natural frequency fd of its free vibration in Hz.
In a free-vibration test of a damped mass–spring system, a displacement peak of 40 mm is followed 2 cycles later by a peak of 8.8 mm. Find the damping ratio ζ.
A 10 kg mass hangs from two springs connected end to end (in series): the upper spring has k₁ = 25 kN/m and the lower one k₂ = 25 kN/m. Ignore damping and the masses of the springs. Find the natural frequency fn of vertical vibration in Hz.
A 10 kg mass hangs from spring k₃ = 80 kN/m. The top of k₃ is attached to a rigid bar that hangs from two springs side by side, k₁ = 80 kN/m and k₂ = 15 kN/m; the bar stays level. Ignore damping and the masses of the springs and bar. Find the natural frequency fn of vertical vibration in Hz.
Answer key
- 1. fn = 5.573 Hz
- 2. fn = 4.985 Hz
- 3. fd = 1.541 Hz
- 4. ζ = 0.1196
- 5. fn = 5.627 Hz
- 6. fn = 10.49 Hz
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