Mechanical vibrations worksheet with answers

Free printable Mechanical vibrations worksheet: 6 problems from easy to exam level, with an answer key. Print it or save it as a PDF.

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1.Easy

A 20 kg mass hangs from a spring with a stiffness of 40 kN/m. Ignore damping. Find the natural frequency f_n in Hz.

m = 20 kgk = 40 kN/m

f_n = Hz

2.Easy

A 5 kg mass hangs from a spring with a stiffness of 5 kN/m. Ignore damping. Find the natural circular frequency ω_n in rad/s.

m = 5 kgk = 5 kN/m

ω_n = rad/s

3.Medium

In a free-vibration test of a damped mass–spring system, a displacement peak of 25 mm is followed one cycle later by a peak of 20.7 mm. Find the damping ratio ζ.

x₀ = 25 mmx₁ = 20.7 mmn = 1

ζ =

4.Medium

A 15 kg mass is supported by a spring with a stiffness of 40 kN/m and a viscous damper with a damping coefficient of 80 N·s/m. Find the damping ratio ζ.

m = 15 kgk = 40 kN/mc = 80 N·s/m

ζ =

5.Hard

A 40 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 = 10 kN/m and k₂ = 50 kN/m; the bar stays level. Ignore damping and the masses of the springs and bar. Find the natural frequency f_n of vertical vibration in Hz.

m = 40 kgk₁ = 10 kN/mk₂ = 50 kN/mk₃ = 12 kN/m

f_n = Hz

6.Hard

A 10 kg mass hangs from two springs side by side (in parallel), with stiffnesses k₁ = 12 kN/m and k₂ = 100 kN/m. The mass stays level. Ignore damping and the masses of the springs. Find the natural frequency f_n of vertical vibration in Hz.

m = 10 kgk₁ = 12 kN/mk₂ = 100 kN/m

f_n = Hz

Answer key

1. f_n = 7.118 Hz
2. ω_n = 31.62 rad/s
3. ζ = 0.03003
4. ζ = 0.05164
5. f_n = 2.516 Hz
6. f_n = 16.84 Hz

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