A machine rests on spring mounts, which compress by 2.5 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 5 kg mass hangs from a spring with a stiffness of 40 kN/m. Ignore damping. Find the natural frequency fn in Hz.
A 20 kg mass is supported by a spring with a stiffness of 4 kN/m and a viscous damper with a damping coefficient of 50 N·s/m. Find the damping ratio ζ.
A 40 kg mass is supported by a spring with a stiffness of 20 kN/m and a viscous damper with a damping coefficient of 90 N·s/m. Find the damping ratio ζ.
A 5 kg mass hangs from spring k₃ = 25 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 = 80 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.
A 5 kg mass hangs from two springs connected end to end (in series): the upper spring has k₁ = 40 kN/m and the lower one k₂ = 5 kN/m. Ignore damping and the masses of the springs. Find the natural frequency fn of vertical vibration in Hz.
Answer key
- 1. fn = 9.97 Hz
- 2. fn = 14.24 Hz
- 3. ζ = 0.08839
- 4. ζ = 0.05031
- 5. fn = 10.47 Hz
- 6. fn = 4.745 Hz
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