| What is meant by a critical speed for rotating machinery? |
| A) The critical speed of a shaft is the speed at which it will shear due to excessive torque placed upon it by the prime mover in driving the load. |
| B) The critical speed of a shaft is the speed of rotation that is out of harmonic synchronism with the shaft's natural vibration frequency which produces excessive vibration. |
| C) The critical speed of a shaft is the speed of rotation that is in harmonic synchronism with the shaft's natural vibration frequency which produces excessive vibration. |
| D) The critical speed of a shaft is the speed at which it will fly apart due to excessive centrifugal forces associated with excessive speed. |
