Aristotle (384-311 BC) was one of the greatest philosophers and scientists of all time. He didn’t focus his attention on the specific study of fluids in motion, but many of his observations of fluids and objects in nature play a role in our current understanding of fluids in motion. For instance, Aristotle correctly surmised that a fluid in a container completely fills the space it occupies, with an observable surface at the top if the container is not completely filled. He also understood that “something” was at work to bring a moving object to a stop. Today we refer to the former concept as continuum and the latter as resistance. Both are important in understanding fluids in motion. Continuum explains why a fluid can be tested at any point in the fluid. Resistance is fundamental to an appreciation of viscosity, the internal friction of a liquid.
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