Kardashev's civilization rating
Boundary shear stress (for natural rivers)
Sum of the ratios on the three altitudes of the distance of the orthocenter from the base to the length of the altitude
Quadrilateral's length of the diagonals
Characteristic Length
NTU method - the effectiveness of a counter-current flow heat exchanger
Friis Transmission equation (with dB units)
Vis-Viva Equation
One-repetition maximum (McGlothin formula)
Damping ratio (related to the percentage overshoot)