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Mechanical Engineering QUESTION #2449
Question 1
Critical speed of a rotating shaft is the shaft speed at which:
  • \(p = \omega_n\) — the rotational speed equals the shaft's natural lateral frequency, causing resonance✔️
  • The shaft material yields due to torsional stress
  • The bearing clearance exceeds the shaft deflection
  • The shaft temperature reaches a critical value
Correct Answer Explanation
The critical speed of a rotating shaft is when \(p=\omega_n\), i.e., the spin speed equals the natural frequency of lateral vibration. At this speed, even small imbalance causes large deflections.