The critical speed of a shaft supported at its ends by bearings can be determined without load by analyzing the natural frequency of the system. The effects of critical speed include potential resonance, which can lead to excessive vibrations and structural damage. Dunkerley's method is often referenced for calculating critical speed, taking into account factors like shaft length and mass distribution. Understanding these dynamics is crucial for ensuring operational stability and longevity of rotating machinery. Proper assessment of critical speed helps in designing effective support systems for shafts.