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.
Mechanical vibrations worksheet with answers
A 40 kg mass hangs from a spring with a stiffness of 10 kN/m. Ignore damping. Find the natural frequency fn in Hz.
A 2 kg mass is supported by a spring with a stiffness of 12 kN/m and a viscous damper with a damping coefficient of 150 N·s/m. Find the damping ratio ζ.
A 40 kg mass on a spring with a stiffness of 20 kN/m has a viscous damper giving a damping ratio of 0.45. Find the damped natural frequency fd of its free vibration in Hz.
A 5 kg mass hangs from two springs side by side (in parallel), with stiffnesses k₁ = 20 kN/m and k₂ = 50 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 25 kg mass hangs from two springs connected end to end (in series): the upper spring has k₁ = 10 kN/m and the lower one k₂ = 30 kN/m. Ignore damping and the masses of the springs. Find the natural frequency fn of vertical vibration in Hz.
Answer key
- 1. fn = 4.985 Hz
- 2. fn = 2.516 Hz
- 3. ζ = 0.4841
- 4. fd = 3.178 Hz
- 5. fn = 18.83 Hz
- 6. fn = 2.757 Hz
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