A machine rests on spring mounts, which compress by 4 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 200 kg mass hangs from a spring with a stiffness of 40 kN/m. Ignore damping. Find the natural circular frequency ωn in rad/s.
A 20 kg mass is supported by a spring with a stiffness of 10 kN/m and a viscous damper with a damping coefficient of 220 N·s/m. Find the damping ratio ζ.
A 50 kg mass is supported by a spring with a stiffness of 200 kN/m and a viscous damper with a damping coefficient of 1580 N·s/m. Find the damping ratio ζ.
A 50 kg mass hangs from two springs side by side (in parallel), with stiffnesses k₁ = 5 kN/m and k₂ = 12 kN/m. The mass stays level. 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 = 12 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 = 12 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 = 7.882 Hz
- 2. ωn = 14.14 rad/s
- 3. ζ = 0.246
- 4. ζ = 0.2498
- 5. fn = 2.935 Hz
- 6. fn = 5.185 Hz
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