In practice, a rotor weighting about 10 tons and 3,000 r.p.m. may be so well balanced that the motion, except for sound, is only just perceptible.

• 实际上，一个重约10吨、3000转/分的转子可以平衡得非常好，以致于除了声音之外，免免强强觉察到它在运动。