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
k = 5 kN/mm = 2 kgx

A 2 kg mass hangs from a spring with a stiffness of 5 kN/m. Ignore damping. Find the natural circular frequency ωn in rad/s.

m = 2 kgk = 5 kN/m
ωn = rad/s
2.Easy
k = 50 kN/mm = 2 kgx

A 2 kg mass hangs from a spring with a stiffness of 50 kN/m. Ignore damping. Find the natural circular frequency ωn in rad/s.

m = 2 kgk = 50 kN/m
ωn = rad/s
3.Medium
k = 100 kN/mζ = 0.4m = 2 kg

A 2 kg mass on a spring with a stiffness of 100 kN/m has a viscous damper giving a damping ratio of 0.4. Find the damped natural frequency fd of its free vibration in Hz.

m = 2 kgk = 100 kN/mζ = 0.4
fd = Hz
4.Medium
k = 40 kN/mc = 280 N·s/mm = 200 kg

A 200 kg mass is supported by a spring with a stiffness of 40 kN/m and a viscous damper with a damping coefficient of 280 N·s/m. Find the damping ratio ζ.

m = 200 kgk = 40 kN/mc = 280 N·s/m
ζ =
5.Hard
k1​ = 10k2​ = 40m = 50 kg

A 50 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 = 40 kN/m. Ignore damping and the masses of the springs. Find the natural frequency fn of vertical vibration in Hz.

m = 50 kgk1 = 10 kN/mk2 = 40 kN/m
fn = Hz
6.Hard
k1​ = 50k2​ = 15m = 40 kg

A 40 kg mass hangs from two springs connected end to end (in series): the upper spring has k₁ = 50 kN/m and the lower one k₂ = 15 kN/m. Ignore damping and the masses of the springs. Find the natural frequency fn of vertical vibration in Hz.

m = 40 kgk1 = 50 kN/mk2 = 15 kN/m
fn = Hz

Answer key

  1. 1. ωn = 50 rad/s
  2. 2. ωn = 158.1 rad/s
  3. 3. fd = 32.62 Hz
  4. 4. ζ = 0.0495
  5. 5. fn = 2.013 Hz
  6. 6. fn = 2.703 Hz

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