perpetual motion

noun

, Mechanics.

the motion of a theoretical mechanism that, without any losses due to friction or other forms of dissipation of energy, would continue to operate indefinitely at the same rate without any external energy being applied to it.

perpetual motion

Also calledperpetual motion of the first kind motion of a hypothetical mechanism that continues indefinitely without any external source of energy. It is impossible in practice because of friction
Also calledperpetual motion of the second kind motion of a hypothetical mechanism that derives its energy from a source at a lower temperature. It is impossible in practice because of the second law of thermodynamics

First recorded in 1585–95

I want to always be in a state of perpetual motion: going somewhere, doing something.

It is a potent part of the Sarkozy brand: he is tireless and in perpetual motion.

The poor soldier had one of those eccentric souls which need perpetual motion.

I suppose I am growing old, for I begin to dislike perpetual motion.

Of course, such a doctrine cannot be true; it would amount to a perpetual motion!

In fact, it is the old story illustrated, that perpetual motion is impossible.

Or, perhaps, a still more lively illustration to some readers may be the idea of perpetual motion.

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