'Kinetic movement': does that make sense?

[Superman514]

Hello there,

I was not sure if this belonged in the Classical Physics forum or the General Physics forum, so my apologies if it's in the wrong place.

This topic is part physics and part linguistics. An acquaintance (someone who has never studied beyond basic high school physics) recently use the terms 'kinetic movement' and 'kinetic motion'. It sounded odd, and somewhat redundant. Kinematics is the study of motion, after all. It's kind of like saying 'big giant' or 'funny joker'. Not only that, but 'kinetic' used as an adjective for movement also sounds odd. It is the adjective form of the noun 'kinesis' which literally means motion/movement. The common use for kinetic is 'kinetic energy', or energy that is the result of motion, and not the other way around.


I'm not an expert of either physics or the English language, so I was hoping someone on this forum would have some insightful words on the subject.

 

[Doc Al]

The only 'insight' I can offer is that your instinct seems correct. 'Kinetic movement' seems redundant and I've never heard such a phrase used (correctly) in a physics context. Sounds like a sloppy, made-up term.

 

[Ken G]

I agree with Doc Al that it is redundant classically, and even though this is the classical section it stands pointing out that if we go to quantum mechanics, the phrase "kinetic movement" is even worse than redundant because it suggests there are multiple forms of movement, only some of which would be considered "kinetic." But in quantum mechanics it is the other way around, there are forms of kinetic energy that don't connect to "movement" in the sense that they don't involve changing the likelihood of where the particle will be found. A classic example is an electron in an atom in its ground state-- such an electron is "stationary" in the sense that none of the likelihoods of any observation you can do on it (including position) will change with time, yet even so, it has an enormous amount of kinetic energy. Such a particle is in the bizarre state of having a zero expectation value of its vector momentum, but a nonzero expectation value of the magnitude of its momentum! Classical language fails us, but you might be tempted to conclude such an electron is "kinetic" without "moving", so there is such a thing as non-motional kinetics rather than non-kinetic motion.