The Froude number appears to be a dimensionless parameter. Dimensionless parameters and the Buckingham Pi Theorem are fundamental to physics, and especially fluid flow. It boils (ha!) down to the ideas that 1) A fundamental law of physics must have consistent units, and 2) Dimensionless quantities function as similarity parameters. The Reynolds Number is arguably the most famous of these (alright, Mach number <sighs>), the ratio of inertial to viscous forces in a fluid flow. ("How much like water divided by how much like honey" is a pretty good heuristic.) You can actually <i>derive</i> fundamental physical laws through dimensional analysis. Powerful stuff. One could do far worse than tracking down as much as one can about these principles as early in one’s engineering or scientific career as possible. It’s as big a shortcut in the hard sciences as Latin is for medicine.